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from quality vendors, these bolts are manufactured to the US Army-Navy (AN) standard, predecessor to Mil-Spec (MS), superseded by the National Aerospace Standard (NAS).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. AN4H-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 AN3 through AN20 Series bolts are superseded by NASM3 through 20 Series.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AN3 through AN20 (REV. 12), Military Specification Sheet: Bolt -Machine, Aircraft [superseded by NASM3 through 20].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 AN3 THRU AN20  is canceled and superseded by NASM3 THRU NASM20.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.

AVIATIONEU NEW ERA ASTM A193 Grade B6 Series stainless steel stud bolts are manufactured from the ferritic grade AISI 410 stainless steel and can be heat-treated and machined to minimum of 110-ksi or 760 Mpa tensile strength. Like other fasteners in this seies, apart from their high tensile strength, they exhibit excellent resistance to corrosion, durability as well as a long functional work life. They can be used in different applications in industries that demand high tensile strength and corrosion resistance. Sourced by certified manufacturers they are competively priced and offered in different diameters and lengths. Sold by the piece (pc.) in increments of 10 pieces with Minimum Order Quantity (MOQ) 100 pieces. Appearing price is for reference only and differentiates based on wanted bolt sizes. Please contact us for a quotation.

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.

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.

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.

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 583 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. 

The NAS1581 Series screws  (also termed as bolts) are high strength, close tolerance, reduced (shear) head, countersunk screws offered as part of our own branded (AVIATIONEU NEW ERA) product lines. They come in different materials and finishes designated by the following letters in their product reference number (SKU) which is formed as a combination of the material, diameter, drive style, grip length and option of the screw:

Materials

(A) or (F) = Alloy Steel, 4140,4340 or 8740, Heat treated to 160-180ksi. Cad 2 plated. Material Code (A) has been superseded by Code (F)

(C) = Corrosion Resistant (A286) Steel, Heat treated to160-190ksi. Cad 2 (optional)

(V) = Titanium (6al-4v) Heat treated to 160-180ksi. No finish. Material Code (V) has been cancelled Dec.1991

Diameters: Numbers 3 to 10

Drive Styles

(R)= Offset Cruciform, (Torq-set) R, for diameters 3,4 & 5.

(T) = Offset Cruciform, (Torq-set) R for diameters 6 and up.

(H) = Dovetail Slot

Grip Lengths

The grip length  for Countersunk Head Fasteners (T in the supplied table) includes the head and extends to the full cylindrical portion of the shank. The Grip Length for NAS1581 Series screws is measured in 1/16ths of an inch. + or - .010

AVIATIONEU NEW ERA NAS1581 Series screws are offered in pieces or kits for convenience and economy. 

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

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. 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 NAS1801/NAS1802 series of machine (non structural) screws are aeronautical standard fully threaded Phillips hexagon head screws replacing those of NAS1096 series of same sizes. NAS1801 screws are made from alloy steel per MIL-S-6049 with a Cadmium finish per QQ-P-416 Type II and feature a 160,000 - 185,000 psi tensile strength. NAS1802 screws are made from A-286 Corrosion Resisting Steel and are passivated per QQ-P-35. They are both offered in different thread sizes and lengths in inches and sold in pieces or packs of specified number of screws indicated after the letters "PK" in the product reference number (SKU). For more information, please refer to the supplied documentation or contact us.

AVIATIONEU NEW ERA Hexagon Socket Head Screws are made of Carbon Steel, Alloy Steel with a Black Oxide or Galvanized finish (depending on the P/N) and a strength class of 4.8 or other as specified by the letter "S" in the P/N. They are fully threaded, coarse type, and produced by certified manufacturers in accordance with DIN 7984 standard. They are offered in competitive prices in different diameters ("M" designated), indicating the screw's diameter in mm and lengths in mm. The thread pitch (the distance between threads measured along the length of the screw) expressed in mm is indicated by the "P" designation in the P/N. Sold in packs of 500, 250 or  50 pieces depending on the selected product. The number of pieces included in each pack is mentioned after "PK" designation.

Tapping screws eliminate the need for drilled holes, as they are designed to cut their own hole as it is screwed into the materials. They are commonly used  in cases when the material is too thin (e.g. sheet metals), there is no rear access for installation of  a nut or when disassembly is required at a later stage and therefore blind rivets can not be an alternative. Sourced from quality producers, tapping screws are offered as part of our own labelled (AVIATIONEU NEW ERA) product lines conforming to aerospace/military or industrial standards/specifications. 

AVIATIONEU NEW ERA AN530 series screws are mil spec tapping screws offered in different sizes and sold in packs. Those with a Philips recessed head are indicated by the letter "R" in the product part number. Tapping screws conforming to ASME specifications are also available as part of AVIATIONEU NEW ERA product portfolio (see separate product presentation). The number of screws per package is indicated 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.

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. AN3H-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.

AVIATIONEU NEW ERA Screw Extraction Kit is intended for use as a removal tool of stuck or broken screws, bolts or studs.

The kit consists of a 6-piece standard screwdriver set and a T Type steel single sided ratchet wrench adjustable to handle fasteners of M3 to M8 sizes. 

It is a high quality, versatile, convenient, efficient and long service life kit that can be used for home and professional applications in bikes, cars, electronics, household appliances, mobile repairs and other uses.

The 6-piece standard screwdriver set and the ratchet wrench can be bought separately although the kit provides a cost effective solution.

AN 22 Series Clevis bolts are available in NEW SURPLUS condition. Availability till stock exhaustion. They are special-purpose bolts with a a slotted brazier type head and used where a large shearing stress occurs (never in tension). Available with drilled or undrilled shank (designated by the letter "A" after the dash number for undrilled shank). 

Boeing & Airbus, the two leading airframe builders, have developed specifications for fasteners, hardware and other parts manufactured by different companies. Compliance with  Boeing (aka BAC) and Airbus (aka ASNA) Standards is a  prerequisite for installation or use of these parts on their respective aircraft. In many cases, Boeing & Airbus fasteners and other parts have the same fit, form, and function and they are considered as alternatives or substitutes to the respective parts designed and/or manufactured by industry leaders such as HI-SHEAR  or HOWMET in the case of fastening products.They also conform to widely accepted Military & Aerospace Standards such as AN, MS, NAS and others. However, caution is required as, depending on their series & conforming standard, fasteners are offered in Imperial (in.), Metric (mm) systems, or  both, with resulting variations in their dimensions and units of measurement of their properties.

As a result of the extensive portfolio of fastening products (including screws and bolts, nuts, washers, pins, rivets, clamps, and many others) from different leading suppliers, and those falling under Boeing, Airbus, Military and Aerospace Standards, these are listed separately in our Web Platform for Supplies.  It must be noted that, depending on the intended application, usually more than one options are available to prospective buyers and selection is finally made, apart from specifications, on the basis of price or lead time required for non-stock parts. Whenever possible,correlation tables and other information and documentation is provided to facilitate the users' awareness on interchangeability of offered fasteners and the selection of the right parts for their intended application. For additional information please 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. AN5H-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.

AVIATIONEU NEW ERA ASTM A324 Grade 8.8 Series high tensile hexagonal head threaded bolts are produced from medium carbon steel with heat treatment by both quenching and tempering.  They comply with ASTM A324, ASME SA324 standards. Medium carbon steel is less expensive  than other grades and features good ductile and malleable qualities but a lower tensile strength. 

Grade 8 Class bolt capabilities: Yield (strech): 4354 lbs min, Tension (failure): 5024 lbs min, Tensile Strength: 150.000 lbs per square inch.

These bolts are offered in different finishes (zinc plated, plain or hot dip galvanised) and different sizes (diameter M20 to M100 mm / 3/4" to 3.1/2").  Sold by the piece (pc.) in increments of 10 pieces with Minimum Order Quantity (MOQ) 100 pieces. Appearing price is for reference only and differentiates based on wanted bolt sizes. Please contact us for a quotation.

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.

AVIATIONEU NEW ERA Hexagon Bolts are made of Stainless Steel 304/316 (depending on the P/N) with a bright surface treatment and a strength class of A2-70 for SS 304 bolts and A4-70 for SS 316 bolts. They are fully threaded, coarse type, and produced by certified manufacturers in accordance with DIN 933 standard. They are offered in competitive prices in different diameters ("M" designated), indicating the bolt's diameter in mm and lengths in mm. The thread pitch (the distance between threads measured along the length of the bolt) expressed in mm is indicated by the "P" designation in the P/N. Sold in packs of 250, 100 or  25 pieces depending on the selected product. The number of pieces included in each pack is mentioned after "PK" designation.

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.

AVIATIONEU NEW ERA AN526 series screws are mil spec truss-head non-structural machine screws made of carbon steel and cadmium plated. Minimum tensile strength 55,000 psi. Available in slot head or Phillips recessed head indicated by the letter "R" in the product part number. They are available in different sizes and lengths in inches and sold in packs. The number of screws per package is indicated 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.

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.