The Washer,flat, cataloged under National Stock Number 5310-00-660-3004, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Miller-Holzwarth Inc.. Government technical data includes 9 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. 4 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-00-660-3004 |
| Primary Part Number | A1990 |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Miller-Holzwarth Inc. |
| Status | ACTIVE |
| Surface Treatment Document and Classification | QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Overall Diameter | 0.688 INCHES NOMINAL IN |
| Cross-Sectional Shape Style | RECTANGULAR |
| Surface Treatment | CADMIUM OVERALL |
| Peripheral Shape Style | ROUND |
| Material | STEEL OVERALL |
| Center Hole Shape Style | ROUND |
| Hole Diameter | 0.448 INCHES NOMINAL IN |
| Thickness | 0.084 INCHES MINIMUM AND 0.094 INCHES MAXIMUM IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| A1990 PRIMARY | Miller-Holzwarth Inc. (USA) |
NSN 5310-00-660-3004 is a Washer,flat, manufactured by Miller-Holzwarth Inc., classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-00-660-3004 has 1 manufacturer part number on file: A1990 (Miller-Holzwarth Inc.).
4 possible matches (shared part number, not a government interchangeability claim): 8455-01-572-7487, 8455-01-572-7497, 8455-01-664-2443. Verify interchangeability with system specifications before substitution.
Key specifications for A1990: Surface Treatment Document and Classification: QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Overall Diameter: 0.688 INCHES NOMINAL IN; Cross-Sectional Shape Style: RECTANGULAR; Surface Treatment: CADMIUM OVERALL. 9 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). 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.