The Heat Sink,electrical-Electronic, cataloged under National Stock Number 5999-01-321-9172, is classified within Federal Supply Class 5999 (Miscellaneous Electrical and Electronic Components) of the Electrical and Electronic Equipment Components group. The manufacturer of record is Northrop Grumman Systems Corporation. Government technical data includes 10 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active. Unit of issue: EA.
| Parameter | Value |
|---|---|
| NSN | 5999-01-321-9172 |
| Primary Part Number | GB21A5 |
| Item Name | Heat Sink,electrical-Electronic |
| FSC / FSG | 5999 / 59 — Miscellaneous Electrical and Electronic Components |
| Manufacturer | Northrop Grumman Systems Corporation |
| Status | ACTIVE |
| Mounting Facility Type and Quantity | 1 UNTHREADED HOLE(S) THIRD MOUNTING FACILITY |
| Mounting Facility Type and Quantity | 5 UNTHREADED HOLE(S) FIRST MOUNTING FACILITY |
| Mounting Facility Type and Quantity | 5 UNTHREADED HOLE(S) SECOND MOUNTING FACILITY |
| Overall Diameter | 1.000 INCHES NOMINAL IN |
| Unthreaded Mounting Hole Diameter | 0.146 INCHES MINIMUM AND 0.152 INCHES MAXIMUM FIRST MOUNTING FACILITY IN |
| Unthreaded Mounting Hole Diameter | 0.165 INCHES MINIMUM AND 0.171 INCHES MAXIMUM SECOND MOUNTING FACILITY IN |
| Unthreaded Mounting Hole Diameter | 0.200 INCHES MINIMUM AND 0.206 INCHES MAXIMUM THIRD MOUNTING FACILITY IN |
| Material Document and Classification | QQ-A-200 FED SPEC SINGLE MATERIAL RESPONSE |
| Surface Treatment | TIN |
| Material | ALUMINUM ALLOY 6061 |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | Possible hazard — SDS may be required (DLA HMIC P) |
| Shelf Life Code | 0 |
| Criticality Code | X |
| Unit of Issue | EA |
| Acquisition advice code | J |
| Weight | 0.0100 lbs |
| Cube | 0.0010 cu ft |
| Part Number | Manufacturer |
|---|---|
| GB21A5 | Northrop Grumman Systems Corporation (USA) |
| Reference | Meaning |
|---|---|
| GB21A5 | 3/2 Design control — primary reference U.S. Government activity |
NSN 5999-01-321-9172 is a Heat Sink,electrical-Electronic, manufactured by Northrop Grumman Systems Corporation, classified under FSC 5999, Miscellaneous Electrical and Electronic Components. Status: active.
NSN 5999-01-321-9172 has 1 manufacturer part number on file: GB21A5 (Northrop Grumman Systems Corporation).
Key specifications for GB21A5: Mounting Facility Type and Quantity: 1 UNTHREADED HOLE(S) THIRD MOUNTING FACILITY; Mounting Facility Type and Quantity: 5 UNTHREADED HOLE(S) FIRST MOUNTING FACILITY; Mounting Facility Type and Quantity: 5 UNTHREADED HOLE(S) SECOND MOUNTING FACILITY; Overall Height: 0.218 INCHES MINIMUM AND 0.234 INCHES MAXIMUM IN. 10 specifications are documented in the U.S. Government catalog.
Possible hazard — SDS may be required (DLA HMIC P). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.