Machine screws are one of the more widely used products among dozens of standard fastener types. They can be either coarse-threaded or fine-threaded, and are usually available with a wide range of head types. Usually stronger than many other screw types, they are used for fastening metal parts and panels securely together in a range of construction and other applications including aerospace, machinery, vehicles, engines, tool assemblies, electronic devices, and large-scale industrial equipment. 

Sourced from quality producers,  machine screws are offered as part of our own labelled (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications. They come in different sizes, head types, materials and thread gradings. 

Machine sccrews meeting National Aerospace Standards (NAS), developed and maintained by the US Aerospace Industries Association (AIA), come in different types and sizes structured in different series, including:

NAS 1101, 1102, 1189, 1190, 1191, 1635, 1801, 1802, 220, 229, 333,  514,  517, 560, 583, 600, 623 και NAS 662.

The NAS 584 series are non structural machine screws are flush head close tolerance machine screws made of aeronautical 100 deg. alloy steel and cadmium plated.  Offered in different thread sizes and lengths in inches as OEM parts of respective manufacturers or as parts of AVIATIONEU NEW ERA product lines. Sold mostly in packs with number of pieces per pack specified after the letters "PK" in the product reference number (SKU). For more information, please refer to the supplied documentation or contact us. 

Structural screws are made of alloy steel, are properly heat treated, and can be used as structural bolts. Those commonly used in aircraft applications are manufactured to aerospace/military standards/specifications. They are offered as part of our own branded (AVIATIONEU NEW ERA) product lines structured in different series based on the standard of their conformance. Some of the screws commonly used include NAS204 through NAS235 and AN509/AN525 series. 

MS24694 Series structural screws have a 100° countersunk Phillips head. They replace the respective AN509 series structural screws of materials and finishes. Minimum tensile strength for steel is 125,000 psi. They are fabricated from alloy steel and cadmium plated per specification QQ-P-416A, Type II, Class 3 or 300 Series Stainless Steel unplated designated by the letters "S" and "C" respectively in the product part number after MS24694 and before the size number.

Sourced from quality suppliers, AVIATIONEU NEW ERA MS24694 series structural screws are offered in different thread sizes and lengths in inches and sold in pieces or packs of specified number of screws designated after the letters "PK" in the product reference number (SKU). For more information, please refer to the individual product presentations, the supplied documentation or contact us.

The NAS1630 Series screws are pan head, short thread, offset cruciform machine screws offered as part of our own branded (AVIATIONEU NEW ERA) product lines. These screws use PHILLIPS Screw-Torq-Set® drive system with significant benefits outlined below. Sourced from quality manufacturers they are offered in alloy steel or corrosion resistant steel (CRES) and different thread sizes and legths in inches. Sold in packs each containing a specified number of screws. The number of screws in each pack is specified after the letters "PK" in the product reference code (SKU).

PHILLIPS Screw-Torq-Set® Drive System Features & Benefits

Offset cruciform shape with straight wing walls for greater torque transfer.

Removal walls larger than drive walls. Facilitates disassembly without drill outs.

Specific driver for each diameter fastener. Assures optimum torque for each size and strong head configuration.

Compatible with standard PHILLIPS ACR® ribbed TORQ-SET® drivers. Allows use of ribbed tools with standard screws

PSC quality inspections. Assures global system quality and compatibility.

Structural screws are made of alloy steel, are properly heat treated, and can be used as structural bolts. Those commonly used in aircraft applications are manufactured to aerospace/military standards/specifications. They are offered as part of our own branded (AVIATIONEU NEW ERA) product lines in different materials and finishes, structured in different series based on the standard of their conformance.

AVIATIONEU NEW ERA MS27039 Series structural machine screws are pan head cross recessed screws equivalent to those of NAS 220 Series. MS27039 Series screws are fabricated from Alloy Steel and Cadmium plated per specification QQ-P-416A, Type II, Class 3, Anodized Aluminum Alloy 2024 or Stainless Steel Unplated  to MIL-S-6050 or MIL-8695 specifications. Those from are designated by the letters "DD" and their counterparts from stainless steel  by the letter "C" respectively in the product part number after MS27039 and before the size number. These screws have 125,000 to 145,000 psi tensile strength. Sourced from quality suppliers, they are offered in different thread sizes and lengths in inches and sold in pieces or convenient packs of specified number of screws per pack indicated after the letters "PK" in the product reference number (SKU).

Other structural screws of NAS204 through NAS235 and AN509/AN525 series are also available (see individual product presentations).

For more information, please refer to the supplied documentation or contact us.

AN hex head bolts in different series are offered under AVIATIONEU NEW ERA product series. Sourced from quality vendors, these bolts are manufactured to the US Army-Navy (AN) standard, predecessor to Mil-Spec (MS), superseded by the National Aerospace Standard (NAS). Commonly used in aviation for either tensile/shear load applications. Made from high-strength type 4037 or 8740 alloy steel or 431 Stainless Steel (CRES) and cadmium plated for superior corrosion resistance (compared to commercial grade zinc plated bolts) they are offered with shank drilled for cotter pin or undrilled for stop nut application, and with a drilled head for safety wire or without. Minimum Tensile Strength (Steel and CRES) - 125,000psi. The length of AN aircraft bolts is measured from under the head to the end of the shank. The "grip" is the unthreaded portion of the shank. Threads are pressed into the steel, not cut, thus maintaining strength throughout the entire shank. The surface under the head of AN bolts is designed to be a bearing surface to reduce non-uniform stress as the bolt is torqued thus reducing premature fatigue. The following letters are used in the product part  numbers.

"A" after the dash number for bolts with undrilled shank

"C"  for bolts made of 431 Stainless Steel (CRES)

"H" after the AN number for bolts with drilled head (eg. AN6H-15)

 AN3 through AN20 Series bolts are superseded by NASM3 through 20 Series. The part numbers in both series have not been changed. 

Specification Details:

AN3 through AN20 (REV. 12), Military Specification Sheet: Bolt -Machine, Aircraft [superseded by NASM3 through 20]. This specification covers aircraft machine bolts part numbers, AN3, AN4, AN5, AN6, AN7, AN8, AN9, AN10, AN14, AN16, AN17, AN18, and AN20. AN3 THRU AN20  is canceled and superseded by NASM3 THRU NASM20. The Part Identification Number (PIN) for AN3 THRU AN20 REV. 12 and the part number for NASM3 THRU NASM20 are identical. The part numbers have not been changed.

Machine screws are one of the more widely used products among dozens of standard fastener types. They can be either coarse-threaded or fine-threaded, and are usually available with a wide range of head types. Usually stronger than many other screw types, they are used for fastening metal parts and panels securely together in a range of construction and other applications including aerospace, machinery, vehicles, engines, tool assemblies, electronic devices, and large-scale industrial equipment. 

Sourced from quality producers,  machine screws are offered as part of our own branded (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications.  They come in different sizes, head types, materials and thread gradings. Countersunk screws allow the head of the screw to sit flush with or below the surface of the surrounding material. They may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges.

AVIATIONEU NEW ERA MS35206 and MS35207 series of machine (non structural) screws are mil spec pan head cross recessed (Phillips) screws, manufactured from carbon steel and are cadmium plated to specification QQ-P-416, Type 2, Class 3. MS35206 series machine screws feature 60,000 psi min. tensile strength and can be used as replacements for AN526 truss head & AN515 round head screws. MS35207 series machine screws are fine threaded have a minimum tensile strength of 55,000 psi and replace the AN507R series. Both MS35206 and MS35207 series machine screws are offered in different diameters, thread sizes and lengths in inches and they are sold in pieces. For more information, please refer to the individual product presentations, the supplied documentation or contact us.

ROTAX® aircraft  engines form part of the product portfolio  of BRP-Powertrain GmbH & Co. KG which develops and manufactures engines for snowmobiles, watercrafts, boats, roadsters, all-terrain and side-by-side vehicles, motorcycles, carts, and aircrafts.

BRP-ROTAX® product range includes certified and non certified internal combustion engines, parts and accessories for light and ultralight aircraft.

Different screws, such as hexagonal, allen, fixation and others are used in BRP-ROTAX® aircraft engines (please refer to the respective product presentations). They come in various sizes (mostly Metric) and are offered as certified or non certified parts from the manufacturer. Non certified parts can be used in ultralights or other aircraft not requiring certification of parts for their installation. Certified parts are designated by the letters "CERT" after the part number in the product reference number (SKU).

Aircraft engine  parts are subject to changes from time to time. Some parts may be no longer available or replaced by others with different part numbers. Listed BRP-ROTAX® engine parts do not imply their current availability or suitability for your engine application. Always consult the most recent Illustrated Part Catalogs (IPCs) or other documentation available from the manufacturer for the correct part number before ordering.

National Aerospace Standard (NAS) machine bolts are commonly used in aircraft, space shuttles, military vehicles, drones, and other high-performance applications. They are offered in different series to meet application requirements.

NAS 6603 Series Steel Cadmium Plated Shear Hex Head Machine Bolts are offered as part of our own labelled (AVIATIONEU NEW ERA) lines of  fasteners. Sourced from quality manufacturers, AVIATIONEU NEW ERA NAS6604 series shear hexagon head bolts conform to the respective U.S. National Aerospace Standard of the Aerospace Industries' Association. They have a 10-32 thread and a nominal grip diameter of 0.1900 inch. NAS6603 series forms part of NAS family of bolts (NAS6603 through NAS6610 series) which includes hex head, close tolerance, alloy steel, long thread, self-locking & non-locking bolts. Their shearing feature is used to minimize damage to more critical components within the application. They are made from alloy steel with cadmium or chromium finishes and offered  in different grips and lengths in inches with undrilled or drilled head and/or shank. Used in applications where a premium-quality, high strength bolt is necessary. The following letters after the basic part numbers specify the material, finish and drilling condition of these bolts.

No Finish Code for cadmium plated bolts

"C" for chromium plated bolts

"D" for drilled shank bolts

"L" for self-locking bolts

"P" for self-locking bolt with patch type locking element

"H" for bolts with drilled head

More than one code letters may be used in sequence.

European Standards (EN) and other deliverables are developed in a large number of sectors by the CEN National Standardization Bodies and CENELEC's National Committees (NCs) of the EU and EFTA countries. Together with the European Telecommunications Standards Institute (ETSI) they are the three European Standardisation Organisations operating under the Regulation (EU) No 1025/2012 to produce European harmonised standards in support of EU legislation and policies.

EN 6114 & EN 6115 Standards relate to short thread countersunk & protruding head bolts respectively for aerospace applications. EN6114 & EN 6115 Standard bolts are commonly used on Airbus commercial aircraft platforns such as A320, A330, A350 and A380. Airbus A320/ A330 aicraft commonly use the alloy steel versions of the EN6114 Standard bolts and those of the Titanium series indicated by the V and T surface coding. The Airbus A350 and A380 models incorporate those from INCONEL®  nickel-chromium-based superalloy. Several HLT, HST, NSA, and VL fasteners can be used as alternates to those of EN6114 Standard (see the supplied documentation).

Sourced from various manufacturers in different materials (steel, titanium or INCONEL® alloys), coatings and sizes, the EN 6114 & EN 6115 Standard bolts are offered as OEM parts of their respective suppliers or as part our own labelled (AVIATIONEU NEW ERA) product lines. Different material letter codes in the part number indicate the material used (e.g. " V" and "T" for Titanium or "L" and "M" for Inconel®). They are sold in packs with the number of bolts included in each pack designated after the letters "PK" in the product reference number (SKU). For additional information please refer to our brochure in our Attachment section

Machine screws are one of the more widely used products among dozens of standard fastener types. They can be either coarse-threaded or fine-threaded, and are usually available with a wide range of head types. Usually stronger than many other screw types, they are used for fastening metal parts and panels securely together in a range of construction and other applications including aerospace, machinery, vehicles, engines, tool assemblies, electronic devices, and large-scale industrial equipment. 

Sourced from quality producers,  machine screws are offered as part of our own branded (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications. They come in different sizes, head types, materials and thread gradings.

Machine sccrews meeting National Aerospace Standards (NAS), developed and maintained by the US Aerospace Industries Association (AIA), are offered in different series.  

AVIATIONEU NEW ERA AIA NAS 623 Series are aeronautical standard non structural pan head cross recess short thread machine screws. They are made from alloy steels 4140 (UNS G41400)  per MIL-S-5626, 4340 (UNS G43400)  per MIL-S-5000 or 8740 (UNS G87400 per MIL-S-6049. They are cadmium plated per QQ-P-416 Type II, Class 2. Heat treatment 160,000 to 180,000 psi ultimate tensile streangth in accordance with SPEC-MIL-H-6875.They are offered in different thread sizes, grips and lengths in inches and sold in pieces or convenient packs of specified number of screws per pack indicated by the number after the letters "PK" in the product reference number (SKU).

For more information, please refer to the supplied documentation or contact us.

AN hex head bolts in different series are offered under AVIATIONEU NEW ERA product series. Sourced from quality vendors, these bolts are manufactured to the US Army-Navy (AN) standard, predecessor to Mil-Spec (MS), superseded by the National Aerospace Standard (NAS). Commonly used in aviation for either tensile/shear load applications. Made from high-strength type 4037 or 8740 alloy steel or 431 Stainless Steel (CRES) and cadmium plated for superior corrosion resistance (compared to commercial grade zinc plated bolts) they are offered with shank drilled for cotter pin or undrilled for stop nut application, and with a drilled head for safety wire or without. Minimum Tensile Strength (Steel and CRES) - 125,000psi. The length of AN aircraft bolts is measured from under the head to the end of the shank. The "grip" is the unthreaded portion of the shank. Threads are pressed into the steel, not cut, thus maintaining strength throughout the entire shank. The surface under the head of AN bolts is designed to be a bearing surface to reduce non-uniform stress as the bolt is torqued thus reducing premature fatigue.  AN3 through AN20 Series bolts are superseded by NASM3 through 20 Series. The part numbers in both series have not been changed. The following letters are used in the product part  numbers.

"A" after the dash number for bolts with undrilled shank

"C"  for bolts made of 431 Stainless Steel (CRES)

"H" after the AN number for bolts with drilled head (eg. AN10H-15)

AN10 bolts have a 5/8-18 thread with a 5/8" shank diameter. All AN10 bolts have a 0.955 thread length regardless of grip length. They can be torqued  to 92-108 lb-ft with AN365 or AN310 full-height nuts, or 50-65 lb-ft with AN364 or MS21042 half-height nuts. Indicated lengths are UHL: Under Head Length (aka Full Shank Length or Overall Length not including bolt head).

Machine screws are one of the more widely used products among dozens of standard fastener types. They can be either coarse-threaded or fine-threaded, and are usually available with a wide range of head types. Usually stronger than many other screw types, they are used for fastening metal parts and panels securely together in a range of construction and other applications including aerospace, machinery, vehicles, engines, tool assemblies, electronic devices, and large-scale industrial equipment. 

Sourced from quality producers,  machine screws are offered as part of our own branded (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications.  They come in different sizes, head types, materials and thread gradings. NAS Standard Machine Screws meet aerospace standards and come in different types and sizes structured in different series including NAS1101, NAS1102, NAS1189, NAS1190, NAS1191, NAS1635, NAS1801, NAS1802, NAS220, NAS229, NAS333, NAS514, NAS517, NAS560, NAS583, NAS600, NAS623 and NAS662.

AVIATIONEU NEW ERA NAS517 series of machine (non structural) screws are aeronautical 100 deg. high strength cross recessed flush head close tolerance machine screws. They are made from alloy steel with a Cadmium finish per QQ-P-416 Type II and feature a 160 - 180 KSI tensile strength. They are both offered in different thread sizes and lengths in inches and sold in pieces. For more information, please refer to the supplied documentation or contact us. 

Different screws used on Textron Aviation Cessna, Beechcraft and Hawker aircraft. Also available as FAA-PMA approved parts from other manufacturers.

AN Clevis bolts are manufactured from nickel steel alloy, SAE 2330 and cadmium plated in same manner as AN3 - AN8 aircraft bolts.They are special-purpose bolts with a a slotted brazier type head and used where a large shearing stress occurs (never in tension). Minimum tensile strength 125,000 PSI. They are available with drilled or undrilled shank (designated by the letter "A" after the dash number for undrilled shank). For the AN12-AN23 bolts the second digit denotes the fine thread machine screw size (e.g. for AN21 the size is 6-40, for AN22 8-36 and for AN23 10-32). For the AN24-AN36 bolts the second digit denotes the diameter in 1/16 inch increments (AN25 has a diameter of 5/16 inch).

Machine screws are one of the more widely used products among dozens of standard fastener types. They can be either coarse-threaded or fine-threaded, and are usually available with a wide range of head types. Usually stronger than many other screw types, they are used for fastening metal parts and panels securely together in a range of construction and other applications including aerospace, machinery, vehicles, engines, tool assemblies, electronic devices, and large-scale industrial equipment. 

Sourced from quality producers,  machine screws are offered as part of our own branded (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications.  They come in different sizes, head types, materials and thread gradings. Countersunk screws allow the head of the screw to sit flush with or below the surface of the surrounding material. They may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges.

AVIATIONEU NEW ERA MS35206 and MS35207 series of machine (non structural) screws are mil spec pan head cross recessed (Phillips) screws, manufactured from carbon steel and are cadmium plated to specification QQ-P-416, Type 2, Class 3. MS35206 series machine screws feature 60,000 psi min. tensile strength and can be used as replacements for AN526 truss head & AN515 round head screws. MS35207 series machine screws are fine threaded have a minimum tensile strength of 55,000 psi and replace the AN507R series. Both MS35206 and MS35207 series machine screws are offered in different diameters, thread sizes and lengths in inches and they are sold in pieces. For more information, please refer to the individual product presentations, the supplied documentation or contact us.

US made bolt machined from 2024T3 aluminum, gold anodized per specification MIL-A-8625C, Type II for improved corrosion resistance. Length 5-3/4". Mounting bolt pattern is four equally spaced 1/4" dia. holes on 1-15/16" dia. bolt circle. Thread size: 1-1/4 x 16. 

National Aerospace Standard (NAS) machine bolts are commonly used in aircraft, space shuttles, military vehicles, drones, and other high-performance applications. They are offered in different series to meet application requirements.

Those of NAS 6203 through NAS 6220 series, superseding their NAS 11(xx) counterparts, are tension hexagon head high strength close tolerance short-thread alloy steel bolts with a minimum tensile strength of 160,000 psi and a minimum shear strength of 95,000 psi. 

They are made from different steel alloys such as 4140 (UNS G41400) or  4340 (UNS G43406) with either Cadmium Plate  Type II, Class 2 or Chromium Plate on shank only with all other surfaces cadmium plated.

Depending on the series they come in different nominal diameters in inches (e.g. NAS 6203 0.1875" (3/16"), NAS 6204 0.25" (1/4"), NAS 6205  0.3125" (5/16"), NAS 6206 0.375" (3/8"), NAS 6208 0.500" 1/2") or NAS 6210 0.625" (5/8") grips (in 1/16” increments beginning at 1/16”), thread and overall fastener lengths. They can be supplied undrilled or with drilled head and/or thread and with or without locking elements (nylon or equivalent). Sourced from quality manufacturers, these bolts are listed according to their series, and offered either as OEM parts or as parts of our own labelled (AVIATIONEU NEW ERA) product lines (see the respective listings). Sold in pieces or packs of specified number of bolts per pack designated by the number after the letters "PK" in the product reference code (SKU).

The following letters after the basic part numbers specify the material, finish, drilling condition, and self-locking capability of these bolts.

No Finish Code for Cadmium II plated bolts

"C" for Chromium plated bolts (shank only)

"L" for Self-locking bolts

"P" for Self-locking bolts with patch type locking element only

Grip Dash Number indicating grip in .0625 increments

"D" after the grip dash number for drilled thread bolts

"H" after the grip dash number for bolts with drilled head

More than one code letters may be used in sequence.

PN Examples:

NAS6204-10 - NAS 6204 Series Bolt, .2500-28 Thread, .625 Grip, Undrilled, Non-locking, Alloy Steel Cadmium II Plated.

NAS6204-10D - Same bolt as above with Drilled Thread.

For more information, please refer to the supplied documentation or contact us.

National Aerospace Standard (NAS) machine bolts are commonly used in aircraft, space shuttles, military vehicles, drones, and other high-performance applications. They are offered in different series to meet application requirements.

NAS 6604 Series Steel Cadmium Plated Shear Hex Head Machine Bolts are offered as part of our own labelled (AVIATIONEU NEW ERA) lines of  fasteners. Sourced from quality manufacturers, AVIATIONEU NEW ERA NAS6604 series shear hexagon head bolts conform to the respective U.S. National Aerospace Standard of the Aerospace Industries' Association. They have a 1/4-28 thread and a nominal grip diameter of 0.2500 inch. NAS6604 series forms part of NAS family of bolts (NAS6603 through NAS6610 series) which includes hex head, close tolerance, alloy steel, long thread, self-locking & non-locking bolts. Their shearing feature is used to minimize damage to more critical components within the application. They are made from alloy steel with cadmium or chromium finishes and offered  in different grips and lengths in inches with undrilled or drilled head and/or shank. Used in applications where a premium-quality, high strength bolt is necessary. The following letters after the basic part numbers specify the material, finish and drilling condition of these bolts.

No Finish Code for cadmium plated bolts

"C" for chromium plated bolts

"D" for drilled shank bolts

"L" for self-locking bolts

"P" for self-locking bolt with patch type locking element

"H"for bolts with drilled head

More than one code letters may be used in sequence.

National Aerospace Standard (NAS) machine bolts are commonly used in aircraft, space shuttles, military vehicles, drones, and other high-performance applications. They are offered in different series to meet application requirements.

Those of NAS 6203 through NAS 6220 series, superseding their NAS 11(xx) counterparts, are tension hexagon head high strength close tolerance short-thread alloy steel bolts with a minimum tensile strength of 160,000 psi and a minimum shear strength of 95,000 psi. 

They are made from different steel alloys such as 4140 (UNS G41400) or  4340 (UNS G43406) with either Cadmium Plate  Type II, Class 2 or Chromium Plate on shank only with all other surfaces cadmium plated.

Depending on the series they come in different nominal diameters in inches (e.g. NAS 6203 0.1875" (3/16"), NAS 6204 0.25" (1/4"), NAS 6205  0.3125" (5/16"), NAS 6206 0.375" (3/8"), NAS 6208 0.500" 1/2") or NAS 6210 0.625" (5/8") grips (in 1/16” increments beginning at 1/16”), thread and overall fastener lengths. They can be supplied undrilled or with drilled head and/or thread and with or without locking elements (nylon or equivalent). Sourced from quality manufacturers, these bolts are listed according to their series, and offered either as OEM parts or as parts of our own labelled (AVIATIONEU NEW ERA) product lines (see the respective listings). Sold in pieces or packs of specified number of bolts per pack designated by the number after the letters "PK" in the product reference code (SKU).

The following letters after the basic part numbers specify the material, finish, drilling condition, and self-locking capability of these bolts.

No Finish Code for Cadmium II plated bolts

"C" for Chromium plated bolts (shank only)

"L" for Self-locking bolts

"P" for Self-locking bolts with patch type locking element only

Grip Dash Number indicating grip in .0625 increments

"D" after the grip dash number for drilled thread bolts

"H" after the grip dash number for bolts with drilled head

More than one code letters may be used in sequence.

PN Examples:

NAS6204-10 - NAS 6204 Series Bolt, .2500-28 Thread, .625 Grip, Undrilled, Non-locking, Alloy Steel Cadmium II Plated.

NAS6204-10D - Same bolt as above with Drilled Thread.

For more information, please refer to the supplied documentation or contact us.

Close tolerance bolts, designed with a greater emphasis on measurement accuracy than other types of bolts, are commonly used in the aerospace manufacturing industry. They are threaded fasteners with a shank and head and a tolerance of just +0.000, -0.0005 inch as an acceptable range of variance. The shank is threaded, thus allowing them to be driven into a threaded hole. They intend to eliminate problems appearing when using traditional bolts which have a greater acceptable range of variance. Close tolerance bolts have closer shank tolerances than that of traditional bolts and fit more securely in threaded holes. For some fastening applications, traditional bolts may suffice. For sensitive fastening applications in which precision is required, close tolerance bolts are typically used. When selecting close tolerance instead of traditional bolts the drive type should be considered. Most close tolerance bolts have a recess within their head that supports a specific bit, such as a Phillips head bit. Regarding their threading, all close tolerance bolts, as well as traditional bolts, have threading. But the way in which the threading is designed may vary. Some bolts have more threading on their shank than others, and some bolts have finer threading than others.

Close tolerance bolts are offered in different materials with high-carbon steel being a common material used in their construction. 

Army & Navy (AN) close tolerance bolts are offered as part of our own labelled (AVIATIONEU NEW ERA) lines of fasteners. They are sourced from quality manufacturers and structured in different series (AN 173/174/175/176/178/180).

The following letters after the basic part numbers specify the material, finish and drilling condition of these bolts.

First Number after AN Basic designates the Diameter. 

"-" for Steel, Cad II plated, no head hole

"C" in place of (-) for Corrosion Resistant Steel (CRES)

"H" in place of (-) or after (C) for bolts with a head hole

"A" In the end of the PN  for bolts with no shank hole