PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

21353Bolt,square Neck

Fastenal Company · NSN 5306-01-646-5549 · FSC 5306 · No Item Name Available
Verified by PartsTable
NSN 5306-01-646-5549 — this item is cataloged by the U.S. Government under National Stock Number 5306-01-646-5549. Primary manufacturer part number: 21353.
Features
  • Bolt,square Neck — FSC 5306
  • Head Height: 0.188 INCHES MINIMUM AND 0.208 INCHES MAXIMUM IN
  • Fastener Length: 0.720 INCHES MINIMUM AND 0.770 INCHES MAXIMUM IN
  • Head Diameter: 0.782 INCHES MINIMUM AND 0.844 INCHES MAXIMUM IN
  • Head Style: ROUND
  • Thread Length: 0.532 INCHES MINIMUM AND 0.551 INCHES MAXIMUM IN
  • Neck Width: 0.368 INCHES MINIMUM AND 0.388 INCHES MAXIMUM IN
  • Thread Class: 2A A
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Overall construction
General Description

The Bolt,square Neck, cataloged under National Stock Number 5306-01-646-5549, is classified within Federal Supply Class 5306 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is Fastenal Company. Government technical data includes 14 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 1 commercial cross-reference from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 8 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN5306-01-646-5549
Primary Part Number21353
Item NameBolt,square Neck
FSC / FSG5306 / 53 — No Item Name Available
ManufacturerFastenal Company
StatusACTIVE
Head Height0.188 INCHES MINIMUM AND 0.208 INCHES MAXIMUM IN
Fastener Length0.720 INCHES MINIMUM AND 0.770 INCHES MAXIMUM IN
Head Diameter0.782 INCHES MINIMUM AND 0.844 INCHES MAXIMUM IN
Head StyleROUND
Thread Length0.532 INCHES MINIMUM AND 0.551 INCHES MAXIMUM IN
Neck Width0.368 INCHES MINIMUM AND 0.388 INCHES MAXIMUM IN
Thread Class2A A
Thread Quantity Per Inch16
Neck Length0.188 INCHES MINIMUM AND 0.219 INCHES MAXIMUM IN
Thread DirectionRIGHT-HAND
Nominal Thread Diameter0.375 INCHES IN
Surface TreatmentZINC OVERALL
MaterialSTEEL OVERALL
Thread Series DesignatorUNIFIED NATIONAL COARSE (UNC)
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 8
3020-00-761-8778190SBD3 INTERCHANGEABLE
Chain,roller
Rexnord Holdings Inc
5340-01-151-706221353 INTERCHANGEABLE
Boot
Bradford Vibrators Co the
4320-01-252-478521353 INTERCHANGEABLE
Connector,fluid,pump
Parker Hannifin Corporation Div Hydraulic Systems Division
5998-01-432-274121353 INTERCHANGEABLE
Circuit Card Assembly
Giga-Tronics Incorporated Dba Giga-Tronics
4810-01-448-759421353-851-1 INTERCHANGEABLE
Sleeve and Slide,directional Con
Sargent Aerospace & Defense, Llc Dba Sargent Controls & Aerospace Div Sargent Controls & Aerospace
4810-01-448-817321353-1002-1 INTERCHANGEABLE
Piston,valve
Sargent Aerospace & Defense, Llc Dba Sargent Controls & Aerospace Div Sargent Controls & Aerospace
3040-01-449-272621353-1000-1 INTERCHANGEABLE
Shaft,shouldered
Sargent Aerospace & Defense, Llc Dba Sargent Controls & Aerospace Div Sargent Controls & Aerospace
6230-01-530-3744 INTERCHANGEABLE
Flashlight
Cross-Reference Index
Part NumberManufacturer
21353 PRIMARY Fastenal Company (USA)
Related Parts
3020-00-761-8778INTERCHANGEABLE
CHAIN,ROLLER
190SBD3
5340-01-151-7062INTERCHANGEABLE
BOOT
21353
4320-01-252-4785INTERCHANGEABLE
CONNECTOR,FLUID,PUMP
21353
5998-01-432-2741INTERCHANGEABLE
CIRCUIT CARD ASSEMBLY
21353
4810-01-448-7594INTERCHANGEABLE
SLEEVE AND SLIDE,DIRECTIONAL CON
21353-851-1
4810-01-448-8173INTERCHANGEABLE
PISTON,VALVE
21353-1002-1
3040-01-449-2726INTERCHANGEABLE
SHAFT,SHOULDERED
21353-1000-1
6230-01-530-3744INTERCHANGEABLE
FLASHLIGHT

Frequently Asked Questions

What is NSN 5306-01-646-5549?

NSN 5306-01-646-5549 is a Bolt,square Neck, manufactured by Fastenal Company, classified under FSC 5306 (No Item Name Available). Status: active.

What are the part numbers for NSN 5306-01-646-5549?

NSN 5306-01-646-5549 has 1 cross-referenced part number: 21353 (Fastenal Company).

What NSN replaces 5306-01-646-5549?

There are 8 known substitutes for 5306-01-646-5549: 3020-00-761-8778, 5340-01-151-7062, 4320-01-252-4785 and 5 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 21353?

Key specifications for 21353: Head Height: 0.188 INCHES MINIMUM AND 0.208 INCHES MAXIMUM IN; Fastener Length: 0.720 INCHES MINIMUM AND 0.770 INCHES MAXIMUM IN; Head Diameter: 0.782 INCHES MINIMUM AND 0.844 INCHES MAXIMUM IN; Part Name Assigned by Controlling Agency: ROUND HEAD, CARRIAGE BOLT. 16 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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