NSN stands for National Stock Number or Nato Stock Number. It’s a number assigned by the DLA mostly for common purchases like nuts and bolts, power supplies, bulbs, connectors, adapters, etc.
NATIONAL or NATO Stock Number
A NATO Stock Number, or National Stock Number (NSN) as it is known in the US, is a 13-digit numeric code, identifying all the ‘standardized material items of supply’ as they have been recognized by all NATO countries including United States Department of Defense. Pursuant to the NATO Standardization Agreements, the NSN has come to be used in all treaty countries. However, many countries that use the NSN program are not members of NATO, e.g. Japan, Australia and New Zealand. A two-digit Material Management Aggregation Code (MMAC) suffix may also be appended, to denote asset end use but it is not considered part of the NSN. An item having an NSN is said to be “stock-listed”.