PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

25-277O-Ring

Hii Unmanned Systems, Inc · NSN 5331-01-621-0738 · FSC 5331 · O-Ring
Verified by PartsTable
NSN 5331-01-621-0738 — this item is cataloged by the U.S. Government under National Stock Number 5331-01-621-0738. Primary manufacturer part number: 25-277.
Features
  • O-Ring — FSC 5331
  • 2 verified cross-references
  • Primary manufacturer: Hii Unmanned Systems, Inc
Applications
  • Fluid containment and leak prevention
  • Pressure boundary maintenance
  • Environmental sealing
General Description

The O-Ring, cataloged under National Stock Number 5331-01-621-0738, is classified within Federal Supply Class 5331 (O-Ring) of the Hardware and Abrasives group. The primary manufacturer of record is Hii Unmanned Systems, Inc. This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 4 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Catalog Facts
Item NameO-Ring
FSC / FSG5331 — O-Ring (FSG 53)
ManufacturersHii Unmanned Systems, Inc (CAGE 4Z5A9); Hydroid, Llc (CAGE 1W8F8)
Technical Specifications
ParameterValue
NSN5331-01-621-0738
Primary Part Number25-277
Item NameO-Ring
FSC / FSG5331 / 53 — O-Ring
ManufacturerHii Unmanned Systems, Inc
StatusACTIVE
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 4
5962-00-199-3824578R823H02 INTERCHANGEABLE
Microcircuit,digital
Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp
3510-01-143-4837 INTERCHANGEABLE
Guard,clothes
5305-01-217-212525277 INTERCHANGEABLE
Screw,cap,hexagon Head
Twg Canada Consolidated Inc
4320-01-538-9032 INTERCHANGEABLE
Pump Unit,rotary
Cross-Reference Index
Part NumberManufacturer
25-277 PRIMARY Hii Unmanned Systems, Inc (USA)
25-277 Hydroid, Llc (USA)
Related Parts
5962-00-199-3824INTERCHANGEABLE
MICROCIRCUIT,DIGITAL
578R823H02
3510-01-143-4837INTERCHANGEABLE
GUARD,CLOTHES
5305-01-217-2125INTERCHANGEABLE
SCREW,CAP,HEXAGON HEAD
25277
4320-01-538-9032INTERCHANGEABLE
PUMP UNIT,ROTARY

Frequently Asked Questions

What is NSN 5331-01-621-0738?

NSN 5331-01-621-0738 is a O-Ring, manufactured by Hii Unmanned Systems, Inc, classified under FSC 5331 (O-Ring). Status: active.

What are the part numbers for NSN 5331-01-621-0738?

NSN 5331-01-621-0738 has 2 cross-referenced part numbers: 25-277 (Hii Unmanned Systems, Inc), 25-277 (Hydroid, Llc).

What NSN replaces 5331-01-621-0738?

There are 4 known substitutes for 5331-01-621-0738: 5962-00-199-3824, 3510-01-143-4837, 5305-01-217-2125 and 1 more. Verify interchangeability with system specifications before substitution.

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