The Washer,flat, cataloged under National Stock Number 5310-01-651-3489, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Hobson Engineering Co Pty Ltd. Government technical data includes 7 specifications, cited from the U.S. Government catalog. The record lists 3 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-651-3489 |
| Primary Part Number | WR43ZM20 |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Hobson Engineering Co Pty Ltd |
| Status | ACTIVE |
| Overall Diameter | 40.4 MILLIMETERS MINIMUM AND 42.0 MILLIMETERS MAXIMUM MM |
| Cross-Sectional Shape Style | RECTANGULAR |
| Peripheral Shape Style | ROUND |
| Material | STEEL OVERALL |
| Center Hole Shape Style | ROUND |
| Hole Diameter | 22.0 MILLIMETERS MINIMUM AND 22.5 MILLIMETERS MAXIMUM MM |
| Thickness | 3.1 MILLIMETERS MINIMUM AND 4.6 MILLIMETERS MAXIMUM MM |
| 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 |
|---|---|
| WR43ZM20 | Hobson Engineering Co Pty Ltd (AUS) |
| HWZSM9204240-01 | Haulmark Trailers (australia) Pty Ltd (AUS) |
| 371200/373027 | Brighton Best Pty Ltd (AUS) |
| Reference | Meaning |
|---|---|
| ASTM F436M | 5/1 Secondary reference U.S. Government activity |
| ASTM F436M-TY1 M20 | 3/2 Design control — primary reference U.S. Government activity |
NSN 5310-01-651-3489 is a Washer,flat, manufactured by Hobson Engineering Co Pty Ltd, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-651-3489 has 3 manufacturer part numbers on file: WR43ZM20 (Hobson Engineering Co Pty Ltd), HWZSM9204240-01 (Haulmark Trailers (australia) Pty Ltd), 371200/373027 (Brighton Best Pty Ltd).
1 possible match (shared part number, not a government interchangeability claim): 5310-01-651-3490. Verify interchangeability with system specifications before substitution.
Key specifications for WR43ZM20: Overall Diameter: 40.4 MILLIMETERS MINIMUM AND 42.0 MILLIMETERS MAXIMUM MM; Cross-Sectional Shape Style: RECTANGULAR; Peripheral Shape Style: ROUND; Material: STEEL OVERALL. 7 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.