A National Stock Number (NSN) is a 13-digit identifier assigned by the Department of Defense to standardize the cataloging of items used across all branches of the U.S. military and federal agencies. The first four digits represent the Federal Supply Class (FSC), which groups items by type, while the remaining nine digits form the National Item Identification Number (NIIN), which uniquely identifies the specific item. You can search NSN-Parts.com directly by NSN, manufacturer part number (MPN), CAGE code, or item name. If you're unsure which NSN applies to your requirement, submit an RFQ with whatever information you have — part number, noun description, application, or platform — and our team will research the correct NSN on your behalf.