National Stock Number
5210-00-203-5371
National Stock Number (NSN) 5210-00-203-5371, or NIIN 002035371, (optical flat) was assigned January 1, 1963 in the Federal Logistics Information System (FLIS). This NIIN is Available for Manual Assignment. This NSN does not replace any other NSNs.
There are 3 manufacturer part numbers associated with this NSN. One of those part number(s) are considered obsolete. The manufacturer part numbers were originally supplied by 3 suppliers. Today, 3 suppliers are listed as Active suppliers for this NSN. Of the active suppliers, only one supplier is deemed design controlled or valid supply parts.
This part number has not been procured by the US Government in over 5 years.
Based on a planned procurement review by the Primary Inventory Control Activity (PICA) on Mar 20, 2019, this NSN's acquisition method was noted as: Acquire directly from the actual manufacturer, whether or not the prime contractor is the actual manufacturer. This part is a commercial/non-developmental/off-the-shelf-item. Valid AMCs: 1, 2, 3, 4 and 5.
This NSN is assigned to Item Name Code (INC) 18274. [A FLAT, TRANSPARENT PIECE OF GLASS, GENERALLY OF FUSED QUARTZ, WITH ONE OR BOTH PRINCIPAL SURFACES POLISHED TO WITHIN A FEW MILLIONTHS OF AN INCH OF A TRUE PLANE. IT IS USED IN CONJUNCTION WITH A MONOCHROMATIC LIGHT SOURCE TO MEASURE THE FLATNESS OF PRECISION FINISHED SURFACES, AND TO DETERMINE THE DISTANCE AND PARALLELISM BETWEEN PRECISION FINISHED SURFACES BY COMPARISON WITH KNOWN STANDARDS. IN OPERATION THE FLAT IS SUPERIMPOSED, REFERENCE SURFACE DOWNWARD, ON THE PARTS UNDER TEST AND WHEN ILLUMINATED BY MONOCHROMATIC LIGHT THE RAYS REFLECTED FROM THE REFERENCE SURFACE ARE EITHER REINFORCED OR NEUTRALIZED BY THE RAYS REFLECTED FROM THE SURFACE UNDER TEST PRODUCING INTERFERENCE BANDS WHICH REVEAL ANY VARIATIONS IN THE THICKNESS OF THE FILM OF AIR BETWEEN SURFACE UNDER TEST AND THE FLAT. EXCLUDES:OPTICAL PARALLELS.]. This item does not have a nuclear hardened feature or any other critical feature such as tolerance, fit restriction or application. There is no data in the HMIRS and the NSN is in an FSC not generally suspected of containing hazardous materials. NSN 5210002035371 does not contain precious metals.
This information was last updated on Jul 01, 2025.