The Bolt,close Tolerance, cataloged under National Stock Number 5306-01-541-5273, is classified within Federal Supply Class 5306 (Bolts) of the Hardware and Abrasives group. The manufacturer of record is Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok. Government technical data includes 18 specifications, cited from the U.S. Government catalog. The record lists 15 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5306-01-541-5273 |
| Primary Part Number | SLB255-L4-19 |
| Item Name | Bolt,close Tolerance |
| FSC / FSG | 5306 / 53 — Bolts |
| Manufacturer | Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok |
| Status | ACTIVE |
| Extended Washer Thickness | 0.036 INCHES NOMINAL IN |
| Head Height | 0.250 INCHES NOMINAL IN |
| Fastener Length | 1.438 INCHES NOMINAL IN |
| Surface Treatment Document and Classification | AMS-QQ-P-35 ASSN STD SINGLE TREATMENT RESPONSE OVERALL |
| Extended Washer Diameter | 0.465 INCHES NOMINAL IN |
| Thread Length | 0.468 INCHES NOMINAL IN |
| Material Document and Classification | PH13-8MO PER AMS 5629 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | SPLINE EXTENDED WASHER |
| Thread Direction | RIGHT-HAND |
| Grip Length | 1.188 INCHES NOMINAL IN |
| Head Minor Diameter | 0.312 INCHES NOMINAL IN |
| Grip Diameter | 0.249 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN |
| Surface Treatment | PASSIVATE OVERALL |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL CORROSION RESISTING OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| 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 |
|---|---|
| S343L4-19 | Huck International, Inc (USA) |
| AIC763L4-19 | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| SLB255-L4-19 PRIMARY | Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok (USA) |
| HP7753L4-19 | Heartland Precision Fasteners Inc (USA) |
| ST3M753L4-19 PRIMARY | The Boeing Company Div Defense (USA) |
| VFK600L4-19 | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| MB156L4-19 PRIMARY | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
| GS1032-L4-19 PRIMARY | B & B Specialties Inc Dba Gs Aerospace Div Gs Aerospace (USA) |
| PBF1267L4-19 | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| ST3M753L4-19 | Houston Precision Fasteners I Lp (USA) |
| MB156L4-19 PRIMARY | Hi-Shear Corporation (USA) |
| VS3190L4-19 | Howmet Global Fastening Systems Inc (USA) |
| ST3M753L4-19 | Fastener Innovation Technology, Inc. Dba F I T (USA) |
| PBF1267L4-19 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| 122897L4-19 PRIMARY | Sps Technologies, Llc Dba PB Fasteners (USA) |
| Reference | Meaning |
|---|---|
| 122897L4-19 | 3/2 Design control — primary reference U.S. Government activity |
| PBF1267L4-19 | 5/9 Secondary reference Sps Technologies Inc |
| PBF1267L4-19 | 5/2 Secondary reference U.S. Government activity |
NSN 5306-01-541-5273 is a Bolt,close Tolerance, manufactured by Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok, classified under FSC 5306, Bolts. Status: active.
NSN 5306-01-541-5273 has 15 manufacturer part numbers on file: S343L4-19 (Huck International, Inc), AIC763L4-19 (Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company), SLB255-L4-19 (Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok), HP7753L4-19 (Heartland Precision Fasteners Inc), ST3M753L4-19 (The Boeing Company Div Defense) and 10 more.
Key specifications for SLB255-L4-19: Extended Washer Thickness: 0.036 INCHES NOMINAL IN; Head Height: 0.250 INCHES NOMINAL IN; Fastener Length: 1.438 INCHES NOMINAL IN; Surface Treatment Document and Classification: AMS-QQ-P-35 ASSN STD SINGLE TREATMENT RESPONSE OVERALL. 18 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.