The Mask,chemical-Biological, cataloged under National Stock Number 4240-01-646-2683, is classified within Federal Supply Class 4240 (Safety and Rescue Equipment) of the Fire Fighting, Rescue, and Safety Equipment group. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government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.
| Item Name | Mask,chemical-Biological |
| FSC / FSG | 4240 — Safety and Rescue Equipment (FSG 42) |
| Parameter | Value |
|---|---|
| NSN | 4240-01-646-2683 |
| Item Name | Mask,chemical-Biological |
| FSC / FSG | 4240 / 42 — Safety and Rescue Equipment |
| Status | ACTIVE |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL F — Mutilate — Cut |
| Hazard | Possible hazard — SDS may be required (DLA HMIC P) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| 72053/2 | 5/9 Secondary reference Avon Protection Systems Incorporated Dba Avon Protection Systems Inc |
| 5-1-4243-70 | 3/2 Design control — primary reference U.S. Government activity |
NSN 4240-01-646-2683 is a Mask,chemical-Biological, classified under FSC 4240, Safety and Rescue Equipment. Status: active.
1 possible match (shared part number, not a government interchangeability claim): 6515-01-655-5993. Verify interchangeability with system specifications before substitution.
Possible hazard — SDS may be required (DLA HMIC P). Hazard information on this page is shown exactly as it appears in the DLA record.
NSN 4240-01-646-2683 has DEMIL Code F. Demilitarization may be required before disposal or transfer to non-military entities.
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.