PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MIL-K-21120Key,socket Head Screw

Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M · NSN 5120-00-189-2985 · FSC 5120 · No Item Name Available
Verified by PartsTable
NSN 5120-00-189-2985 — this item is cataloged by the U.S. Government under National Stock Number 5120-00-189-2985. Primary manufacturer part number: MIL-K-21120.
Features
  • Key,socket Head Screw — FSC 5120
  • Style Designator: L-HANDLE
  • Material: COPPER ALLOY OVERALL
  • Short Arm Length: 1.750 INCHES NOMINAL IN
  • Specification/standard Data: 05047-ASME B18.3 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
  • Wrenching Surface Shape: HEXAGON BOTH ENDS EXTERNAL
  • Long Arm Length: 5.250 INCHES NOMINAL IN
  • Wrenching Surface Size: 0.438 INCHES NOMINAL BOTH ENDS IN
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Copper Alloy Overall construction
General Description

The Key,socket Head Screw, cataloged under National Stock Number 5120-00-189-2985, is classified within Federal Supply Class 5120 (No Item Name Available) of the Hand Tools group. The primary manufacturer of record is Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M. Government technical data includes 8 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 7 commercial cross-references from 6 manufacturers, 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
NSN5120-00-189-2985
Primary Part NumberMIL-K-21120
Item NameKey,socket Head Screw
FSC / FSG5120 / 51 — No Item Name Available
ManufacturerMilitary Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
StatusACTIVE
Style DesignatorL-HANDLE
MaterialCOPPER ALLOY OVERALL
Short Arm Length1.750 INCHES NOMINAL IN
Specification/standard Data05047-ASME B18.3 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
Wrenching Surface ShapeHEXAGON BOTH ENDS EXTERNAL
Long Arm Length5.250 INCHES NOMINAL IN
Wrenching Surface Size0.438 INCHES NOMINAL BOTH ENDS IN
Features ProvidedNONMAGNETIC AND NONSPARKING
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
4730-00-028-70214738-4-4B INTERCHANGEABLE
Adapter,straight,pipe to Hose
Danfoss Power Solutions II, Llc
9905-00-045-3627L-11 INTERCHANGEABLE
Holder,card-Label
Aigner Index Inc
3120-00-148-7742L11 INTERCHANGEABLE
Bushing,sleeve
Circor Naval Solutions Llc Dba Warren Pumps
6240-00-151-5209 INTERCHANGEABLE
Lamp,incandescent
5120-00-189-2979L-17 INTERCHANGEABLE
Key,socket Head Screw
Ngk Metals Corporation Dba N G K Berylco
5120-00-189-2980L-16 INTERCHANGEABLE
Key,socket Head Screw
Ngk Metals Corporation Dba N G K Berylco
5120-00-189-2981L-15 INTERCHANGEABLE
Key,socket Head Screw
Ngk Metals Corporation Dba N G K Berylco
5120-00-189-29825120-00-189-2982 INTERCHANGEABLE
Key,socket Head Screw
General Services Administration Federal Supply Service
5120-00-189-2983L-13 INTERCHANGEABLE
Key,socket Head Screw
Ngk Metals Corporation Dba N G K Berylco
5120-00-189-2984 INTERCHANGEABLE
Key,socket Head Screw
Cross-Reference Index
Part NumberManufacturer
MIL-K-21120 Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M
L-11-2591 Ngk Metals Corporation Dba N G K Berylco (USA)
B18.3 The American Society of Mechanical Engineers (USA)
W-1050-S Ampco Partners, Ltd. Dba Ampco Safety Tools (USA)
A-A-2477 Federal Commercial Item Description Promulgated by General Services Administration Washington DC (USA)
L-11 Ngk Metals Corporation Dba N G K Berylco (USA)
W-1050-S Ampco Metal Inc. Dba Ampco Metal Inc (USA)
Related Parts
4730-00-028-7021INTERCHANGEABLE
ADAPTER,STRAIGHT,PIPE TO HOSE
4738-4-4B
9905-00-045-3627INTERCHANGEABLE
HOLDER,CARD-LABEL
L-11
3120-00-148-7742INTERCHANGEABLE
BUSHING,SLEEVE
L11
6240-00-151-5209INTERCHANGEABLE
LAMP,INCANDESCENT
5120-00-189-2979INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
L-17
5120-00-189-2980INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
L-16
5120-00-189-2981INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
L-15
5120-00-189-2982INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-189-2982
5120-00-189-2983INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
L-13
5120-00-189-2984INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-189-2986INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-189-2986
5120-00-189-2987INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-189-2987

Frequently Asked Questions

What is NSN 5120-00-189-2985?

NSN 5120-00-189-2985 is a Key,socket Head Screw, manufactured by Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M, classified under FSC 5120 (No Item Name Available). Status: active.

What are the part numbers for NSN 5120-00-189-2985?

NSN 5120-00-189-2985 has 7 cross-referenced part numbers: MIL-K-21120 (Military Specifications Promulgated by Military Departments/agencies Under Authority of Defense Standardization Manual 4120 3-M), L-11-2591 (Ngk Metals Corporation Dba N G K Berylco), B18.3 (The American Society of Mechanical Engineers), W-1050-S (Ampco Partners, Ltd. Dba Ampco Safety Tools), A-A-2477 (Federal Commercial Item Description Promulgated by General Services Administration Washington DC) and 2 more.

What NSN replaces 5120-00-189-2985?

There are 12 known substitutes for 5120-00-189-2985: 4730-00-028-7021, 9905-00-045-3627, 3120-00-148-7742 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of MIL-K-21120?

Key specifications for MIL-K-21120: Style Designator: L-HANDLE; Material: COPPER ALLOY OVERALL; Short Arm Length: 1.750 INCHES NOMINAL IN; Specification/standard Data: 05047-ASME B18.3 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD. 9 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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