The Window,optical Instrument, cataloged under National Stock Number 1240-00-171-7900, is classified within Federal Supply Class 1240 (Optical Sighting and Ranging Equipment) of the Fire Control Equipment group. The manufacturer of record is Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier. 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 | 1240-00-171-7900 |
| Primary Part Number | 278694PC6 |
| Item Name | Window,optical Instrument |
| FSC / FSG | 1240 / 12 — Optical Sighting and Ranging Equipment |
| Manufacturer | Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier |
| Status | ACTIVE |
| FSC Application Data | TELESCOPE MK 61 MODS 0-5 |
| Bevel Depth | 1.100 MILLIMETERS NOMINAL MM |
| Material Document and Classification | JAN-G-174, TYPE 517-645, GRADE C MIL SPEC SINGLE MATERIAL RESPONSE LOCATION NOT OTHERWISE SPECIFIED |
| Diameter | 46.000 MILLIMETERS NOMINAL MM |
| Reflection Reducing Surface | BOTH |
| Polished Periphery | NOT PROVIDED |
| Bevel Angle in Deg | 45.000 NOMINAL |
| Material | GLASS OPTICAL LOCATION NOT OTHERWISE SPECIFIED |
| Refraction Index | 1.5170 NOMINAL |
| Polished Surface | BOTH |
| Thickness | 4.800 MILLIMETERS NOMINAL MM |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL D — Destroy Item |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| 278694PC6 PRIMARY | Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier (USA) |
NSN 1240-00-171-7900 is a Window,optical Instrument, manufactured by Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier, classified under FSC 1240, Optical Sighting and Ranging Equipment. Status: active.
NSN 1240-00-171-7900 has 1 manufacturer part number on file: 278694PC6 (Navair and Navsea Managed Original Design Activity Dwg Not Material/parts Supplier).
Key specifications for 278694PC6: FSC Application Data: TELESCOPE MK 61 MODS 0-5; Bevel Depth: 1.100 MILLIMETERS NOMINAL MM; Material Document and Classification: JAN-G-174, TYPE 517-645, GRADE C MIL SPEC SINGLE MATERIAL RESPONSE LOCATION NOT OTHERWISE SPECIFIED; Diameter: 46.000 MILLIMETERS NOMINAL MM. 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.
NSN 1240-00-171-7900 has DEMIL Code D. 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.