PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

45121Screw,cap,socket Head

Safety Socket Llc · NSN 5305-01-591-5777 · FSC 5305 · No Item Name Available
Verified by PartsTable
NSN 5305-01-591-5777 — this item is cataloged by the U.S. Government under National Stock Number 5305-01-591-5777. Primary manufacturer part number: 45121.
Features
  • Screw,cap,socket Head — FSC 5305
  • Thread Length: 1.810 INCHES NOMINAL IN
  • Head Style: PAN NO. 2
  • Head Height: 0.368 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN
  • Thread Quantity Per Inch: 24
  • Internal Drive Style: HEXAGON
  • Head Diameter: 0.550 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
  • Nominal Thread Diameter: 0.375 INCHES IN
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Overall construction
General Description

The Screw,cap,socket Head, cataloged under National Stock Number 5305-01-591-5777, is classified within Federal Supply Class 5305 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is Safety Socket Llc. Government technical data includes 13 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. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN5305-01-591-5777
Primary Part Number45121
Item NameScrew,cap,socket Head
FSC / FSG5305 / 53 — No Item Name Available
ManufacturerSafety Socket Llc
StatusACTIVE
Thread Length1.810 INCHES NOMINAL IN
Head StylePAN NO. 2
Head Height0.368 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN
Thread Quantity Per Inch24
Internal Drive StyleHEXAGON
Head Diameter0.550 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
Nominal Thread Diameter0.375 INCHES IN
Thread Class3A A
Width Across Flats0.312 INCHES NOMINAL IN
Thread DirectionRIGHT-HAND
Fastener Length3.000 INCHES NOMINAL IN
Thread Series DesignatorUNRF
MaterialSTEEL OVERALL
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
5365-00-050-7939 INTERCHANGEABLE
Plug,machine Thread
4310-00-397-312645121 INTERCHANGEABLE
Ring,piston
Leroi International Inc Dba Compair Leroi
3455-00-455-9096B-12 INTERCHANGEABLE
Cutter,milling,end
Pohl Tool Co
5955-00-795-462245121 INTERCHANGEABLE
Oscillating Group
L3harris Technologies, Inc. Div Space and Airborne Systems
5110-01-011-3881 INTERCHANGEABLE
Stripper,wire,hand
2510-01-096-949645121 INTERCHANGEABLE
Spring Assembly,leaf
Hme, Inc. Dba Hme Ahrens-Fox
5365-01-238-0422 INTERCHANGEABLE
Ring,special
5930-01-322-451345121 INTERCHANGEABLE
Switch,flow
Setra Systems, Inc. Dba Gems Sensors
5930-01-354-9794 INTERCHANGEABLE
Switch,toggle
3455-01-365-1664307-13 INTERCHANGEABLE
Cutter,milling,side
Kennametal Inc. Div Kennametal Industrial Products Group
Cross-Reference Index
Part NumberManufacturer
45121 PRIMARY Safety Socket Llc (USA)
Related Parts
5365-00-050-7939INTERCHANGEABLE
PLUG,MACHINE THREAD
4310-00-397-3126INTERCHANGEABLE
RING,PISTON
45121
3455-00-455-9096INTERCHANGEABLE
CUTTER,MILLING,END
B-12
5955-00-795-4622INTERCHANGEABLE
OSCILLATING GROUP
45121
5110-01-011-3881INTERCHANGEABLE
STRIPPER,WIRE,HAND
2510-01-096-9496INTERCHANGEABLE
SPRING ASSEMBLY,LEAF
45121
5365-01-238-0422INTERCHANGEABLE
RING,SPECIAL
5930-01-322-4513INTERCHANGEABLE
SWITCH,FLOW
45121
5930-01-354-9794INTERCHANGEABLE
SWITCH,TOGGLE
3455-01-365-1664INTERCHANGEABLE
CUTTER,MILLING,SIDE
307-13
5340-01-432-4007INTERCHANGEABLE
STRAP,RETAINING
45121
7025-01-642-1899INTERCHANGEABLE
INTERFACE UNIT,AUTOMATIC DATA PR
45121

Frequently Asked Questions

What is NSN 5305-01-591-5777?

NSN 5305-01-591-5777 is a Screw,cap,socket Head, manufactured by Safety Socket Llc, classified under FSC 5305 (No Item Name Available). Status: active.

What are the part numbers for NSN 5305-01-591-5777?

NSN 5305-01-591-5777 has 1 cross-referenced part number: 45121 (Safety Socket Llc).

What NSN replaces 5305-01-591-5777?

There are 12 known substitutes for 5305-01-591-5777: 5365-00-050-7939, 4310-00-397-3126, 3455-00-455-9096 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 45121?

Key specifications for 45121: Thread Length: 1.810 INCHES NOMINAL IN; Head Style: PAN NO. 2; Head Height: 0.368 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN; End Item Identification: STRYKER. 15 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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