Products with NATO Stock number have assigned an NSN number by NATO and are standardized and approved for use in NATO armies, and such a number can also serve as a quality mark that civilians can follow.
Only products that meet the quality requirements for NATO armies are included in the NSN (NATO Stock Number) program. NSN numbers are used by all countries that are under NATO contract, but not only those - non-NATO countries using NSN numbers include Japan, Australia and New Zealand.
Each product has its own unique NSN number, which cannot be used on any other item even after this product has been taken out of production. The NSN number has a 13-digit format and can be written both as a whole or in certain places separated by commas for better readability. The first four positions are the so-called NATO Supply Classification Code (NSC), the other two positions have the code for the National Codification Office (NCB) and the last three and four indicate a specific item.
You can recognize NSN products by this image.
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