The Washer,flat, cataloged under National Stock Number 5310-01-115-3749, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is The Boeing Company Div Defense. Government technical data includes 11 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. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-115-3749 |
| Primary Part Number | ST4M203-4 |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | The Boeing Company Div Defense |
| Status | ACTIVE |
| Surface Treatment Document and Classification | MIL-C-8837 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Overall Diameter | 0.500 INCHES MAXIMUM IN |
| Hardness Rating | 40.0 ROCKWELL C MINIMUM AND 44.0 ROCKWELL C MAXIMUM |
| Material Document and Classification | MIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Cross-Sectional Shape Style | RECTANGULAR |
| Color | BLUE, LIGHT OVERALL |
| Surface Treatment | CADMIUM OVERALL |
| Peripheral Shape Style | ROUND |
| Material | STEEL COMP 4130 OVERALL |
| Center Hole Shape Style | ROUND |
| Thickness | 0.032 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 |
|---|---|
| ST4M203-4 PRIMARY | The Boeing Company Div Defense (USA) |
NSN 5310-01-115-3749 is a Washer,flat, manufactured by The Boeing Company Div Defense, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-115-3749 has 1 manufacturer part number on file: ST4M203-4 (The Boeing Company Div Defense).
Key specifications for ST4M203-4: Surface Treatment Document and Classification: MIL-C-8837 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL; Overall Diameter: 0.500 INCHES MAXIMUM IN; Hardness Rating: 40.0 ROCKWELL C MINIMUM AND 44.0 ROCKWELL C MAXIMUM; Material Document and Classification: MIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL. 11 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.