PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

5255Adapter,socket Wrench

The Stanley Works Dba Stanley Proto · NSN 5120-01-399-9755 · FSC 5120 · No Item Name Available
Verified by PartsTable
NSN 5120-01-399-9755 — this item is cataloged by the U.S. Government under National Stock Number 5120-01-399-9755. Primary manufacturer part number: 5255.
Features
  • Adapter,socket Wrench — FSC 5120
  • Style Designator: EXTERNAL-INTERNAL
  • Features Provided: MANUAL TOOL
  • Drive End Shape: SQUARE SECOND END EXTERNAL
  • Drive End Shape: SQUARE FIRST END INTERNAL
  • Drive Surface Size: 0.250 INCHES NOMINAL SECOND END IN
  • Outside Diameter: 0.687 INCHES MAXIMUM IN
  • Drive Surface Size: 0.375 INCHES NOMINAL FIRST END IN
Applications
  • Applications requiring Steel Overall construction
General Description

The Adapter,socket Wrench, cataloged under National Stock Number 5120-01-399-9755, is classified within Federal Supply Class 5120 (No Item Name Available) of the Hand Tools group. The primary manufacturer of record is The Stanley Works Dba Stanley Proto. Government technical data includes 9 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 10 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN5120-01-399-9755
Primary Part Number5255
Item NameAdapter,socket Wrench
FSC / FSG5120 / 51 — No Item Name Available
ManufacturerThe Stanley Works Dba Stanley Proto
StatusACTIVE
Style DesignatorEXTERNAL-INTERNAL
Features ProvidedMANUAL TOOL
Drive End ShapeSQUARE SECOND END EXTERNAL
Drive End ShapeSQUARE FIRST END INTERNAL
Drive Surface Size0.250 INCHES NOMINAL SECOND END IN
Outside Diameter0.687 INCHES MAXIMUM IN
Drive Surface Size0.375 INCHES NOMINAL FIRST END IN
MaterialSTEEL OVERALL
Surface TreatmentCHROMIUM OVERALL
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 10
3040-00-119-4646525-5 INTERCHANGEABLE
Gearshaft,spur
Ontic Engineering & Manufacturing, Inc Dba Ontic Us
5935-00-502-74818108220 INTERCHANGEABLE
Connector,plug,electrical
Us Army Aviation and Missile Command
5935-00-880-5050148809-1 INTERCHANGEABLE
Connector,receptacle,electrical
L3harris Technologies, Inc. Dba Harris Corp Div Antenna Products
5975-00-913-9183STB-90125 INTERCHANGEABLE
Box Connector,electrical
Egs Electrical Group Appleton Div
5915-00-938-5309SMC344550 INTERCHANGEABLE
Filter Assembly,electrical
Us Army Communications & Electronics Materiel Readiness Command Logistics Engineering Dir
4330-01-117-2553 INTERCHANGEABLE
Clamp
5310-01-171-81255-255 INTERCHANGEABLE
Washer,flat
Crane Pumps & Systems Pft Corp Div Crane Pumps & System Pft Corp.
6110-01-226-46816388 INTERCHANGEABLE
Voltage Regulator Subassembly
893 Mfg, Llc
3120-01-408-53722-123-007-454-05 INTERCHANGEABLE
Bearing,sleeve
Viking Pump, Inc
5340-01-598-85075255 INTERCHANGEABLE
Stop,mechanical
Meritor Industrial Products, Llc
Cross-Reference Index
Part NumberManufacturer
1AF67 W.w. Grainger, Inc. Div Government Sales Division (USA)
5255 PRIMARY The Stanley Works Dba Stanley Proto (USA)
Related Parts
3040-00-119-4646INTERCHANGEABLE
GEARSHAFT,SPUR
525-5
5935-00-502-7481INTERCHANGEABLE
CONNECTOR,PLUG,ELECTRICAL
8108220
5935-00-880-5050INTERCHANGEABLE
CONNECTOR,RECEPTACLE,ELECTRICAL
148809-1
5975-00-913-9183INTERCHANGEABLE
BOX CONNECTOR,ELECTRICAL
STB-90125
5915-00-938-5309INTERCHANGEABLE
FILTER ASSEMBLY,ELECTRICAL
SMC344550
4330-01-117-2553INTERCHANGEABLE
CLAMP
5310-01-171-8125INTERCHANGEABLE
WASHER,FLAT
5-255
6110-01-226-4681INTERCHANGEABLE
VOLTAGE REGULATOR SUBASSEMBLY
6388
3120-01-408-5372INTERCHANGEABLE
BEARING,SLEEVE
2-123-007-454-05
5340-01-598-8507INTERCHANGEABLE
STOP,MECHANICAL
5255

Frequently Asked Questions

What is NSN 5120-01-399-9755?

NSN 5120-01-399-9755 is a Adapter,socket Wrench, manufactured by The Stanley Works Dba Stanley Proto, classified under FSC 5120 (No Item Name Available). Status: active.

What are the part numbers for NSN 5120-01-399-9755?

NSN 5120-01-399-9755 has 2 cross-referenced part numbers: 1AF67 (W.w. Grainger, Inc. Div Government Sales Division), 5255 (The Stanley Works Dba Stanley Proto).

What NSN replaces 5120-01-399-9755?

There are 10 known substitutes for 5120-01-399-9755: 3040-00-119-4646, 5935-00-502-7481, 5935-00-880-5050 and 7 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 5255?

Key specifications for 5255: Style Designator: EXTERNAL-INTERNAL; Features Provided: MANUAL TOOL; Drive End Shape: SQUARE SECOND END EXTERNAL; Overall Length: 1.062 INCHES NOMINAL IN. 10 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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