The Screw,cap,socket Head, cataloged under National Stock Number 5305-01-284-9678, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is The American Society of Mechanical Engineers. Government technical data includes 20 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through both NSN and commercial part number lookups. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-284-9678 |
| Primary Part Number | B1821BH125F500L |
| Item Name | Screw,cap,socket Head |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | The American Society of Mechanical Engineers |
| Status | ACTIVE |
| Head Height | 0.749 INCHES MINIMUM AND 0.813 INCHES MAXIMUM IN |
| Fastener Length | 4.812 INCHES MINIMUM AND 5.000 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE FASTENER |
| Thread Length | 2.750 INCHES MINIMUM AND 2.938 INCHES MAXIMUM IN |
| Hardness Rating | 32.0 ROCKWELL C MINIMUM AND 38.0 ROCKWELL C MAXIMUM FASTENER |
| Material Document and Classification | SAE J429 GR 8 ASSN STD SINGLE MATERIAL RESPONSE FASTENER |
| Nominal Thread Diameter | 1.250 INCHES IN |
| Head Style | HEXAGON |
| Thread Direction | RIGHT-HAND |
| Width Between Flats | 1.812 INCHES MINIMUM AND 1.875 INCHES MAXIMUM IN |
| Nondefinitive Spec/std Data | 2 TYPE AND 10P STYLE AND 8 GRADE |
| Locking Feature | PATCH OR STRIP THREADS |
| Surface Treatment | CADMIUM AND CHROMATE FASTENER |
| Minimum Tensile Strength | 150000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | W/O INTERNAL DRIVE |
| Thread Class | 2A A |
| Thread Quantity Per Inch | 12 |
| Material | PLASTIC POLYAMIDE NYLON LOCKING FEATURE |
| Material | STEEL FASTENER |
| Thread Series Designator | UNF |
| 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 |
|---|---|
| B1821BH125F500L PRIMARY | The American Society of Mechanical Engineers (USA) |
| Reference | Meaning |
|---|---|
| FF-S-85C TYPE II STYLE 10P | 4/1 Identification reference U.S. Government activity |
| M18240 1.250-12UNF-2A 5.000LG | C/1 Advisory reference — outside the item-of-supply concept U.S. Government activity |
| MS90727-281L | 5/9 Secondary reference U.S. Government activity |
| MIL-F-18240,CONF-B HEX HEAD | C/1 Advisory reference — outside the item-of-supply concept U.S. Government activity |
| MIL-F-18240,C0N F-B HEX HEAD | C/1 Advisory reference — outside the item-of-supply concept Zf Industrieantriebe Witten Gmbh |
NSN 5305-01-284-9678 is a Screw,cap,socket Head, manufactured by The American Society of Mechanical Engineers, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-284-9678 has 1 manufacturer part number on file: B1821BH125F500L (The American Society of Mechanical Engineers).
Key specifications for B1821BH125F500L: Head Height: 0.749 INCHES MINIMUM AND 0.813 INCHES MAXIMUM IN; Fastener Length: 4.812 INCHES MINIMUM AND 5.000 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE FASTENER; Thread Length: 2.750 INCHES MINIMUM AND 2.938 INCHES MAXIMUM IN. 20 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.