Short answer: A National Stock Number is 13 digits. The first four are the Federal Supply Class. The last nine are the National Item Identification Number, the NIIN. The first two digits of the NIIN are the National Codification Bureau code. 00 and 01 mean the United States codified the item. DIBBS search uses the full NSN. The NIIN is the part of that number that identifies the item inside the class.
The 13 digits
Take NSN 5340-01-165-7717, a loop clamp. Written with the dashes DLA uses, it splits like this:
- 5340 is the Federal Supply Class, Hardware, Commercial. Those four digits are what you save in a DIBBS FSC alert. The item name on this stock record is Clamp, loop.
- 01-165-7717 is the NIIN, nine digits. Drop the dashes and it is 011657717.
- 01, the first two of the NIIN, is the National Codification Bureau code. Codes 00 and 01 are the United States. Another country’s bureau uses its own two-digit code when that country codified the item. The item can still be bought by DLA.
- 165-7717 is the item number that bureau assigned, seven digits.
The dashes are formatting. On a solicitation and in a search box the number is often the 13 digits with no dashes: 5340011657717. Both are the same NSN. The record is on NSN 5340-01-165-7717. A definition of the whole number is on what is an NSN.
Why the split matters on a DIBBS quote
DLA buys the NSN, not your shop’s internal part number. The RFQ line carries the NSN, a nomenclature, a quantity, and often an approved manufacturer CAGE and part number. If you only have a commercial part number, you still have to land on the NSN before you know whether that RFQ is your item. The search path is NSN lookup by part number.
Use the pieces on purpose:
- Search DIBBS by the 13-digit NSN when you know the exact item. That is the filter in search DIBBS by NSN.
- Search or alert by the four-digit FSC when you can make the class and you do not yet have every NSN. An FSC alert is wide. Watching 5340 returns the whole hardware class, not only the loop clamp.
- Keep the NIIN when someone sends you a “stock number” that is only nine digits. Put the FSC back on the front before you search. 011657717 is not a complete search key until you know the class is 5340.
The NIIN is the item. The FSC classifies it, and DLA can update the class without issuing a new NIIN. Read the nomenclature and the approved part number on the RFQ. Do not quote from the nine digits alone.
What the NIIN does not tell you
The NIIN does not say whether you are allowed to quote. That is the Acquisition Method Suffix Code on the item, the approved-source list, and any qualified-products requirement. A matching NIIN with AMSC C is still an approved-source buy. Decode the letter on the AMSC decoder and read approved source on DIBBS before you price it.
The NIIN also does not say what DLA last paid, how many it bought, or whether the last award was surplus. That sits in the procurement-history table inside the RFQ. See how to price a DLA quote from procurement history.
Packaging is not in the number either. Section B of the RFQ carries the MIL-STD-2073 code string or an ASTM D3951 callout, and marking under MIL-STD-129. Decode the string with the packaging code decoder before you treat two quotes for the same NIIN as the same job.
FSC, NIIN, and the account alerts
On the DIBBS supplier profile you can store FSCs, NSNs, and approved-manufacturer CAGEs. DLA’s registration guide says not to enter an NSN whose FSC is already in the FSC list. The FSC alert already covers that item, and the inbox gets the whole class. Put specific NSNs in the NSN field only for items outside the classes you are already watching, or instead of a class when the class is too broad.
If you are new to the account, the registration order is SAM.gov, then the CAGE, then DIBBS. The steps are in how to register for DIBBS.
Where FedOpp fits
Ask CCO, FedOpp's AI Chief Contracting Officer, answers questions about an NSN or NIIN on the open RFQ, using the item and award history in the same login.
FedOpp matches DIBBS RFQs to the NSNs on your Match Profile and shows the NIIN’s item with the last price, the last-award CAGE, and the AMSC on one row. You can also watch a single NSN. The lookup and the quote still happen on your side: confirm the part number, then submit on DIBBS. FedOpp is $199 a month after a 7-day free trial.
Frequently asked questions
What is the difference between a NIIN and an NSN?
The NSN is 13 digits. The NIIN is the last nine of those digits. The first four digits of the NSN are the Federal Supply Class and are not part of the NIIN.
What do the first two digits of a NIIN mean?
They are the National Codification Bureau code, the country that codified the item. 00 and 01 are the United States.
Is a nine-digit number enough to search DIBBS?
Use the 13-digit NSN. A nine-digit NIIN needs the Federal Supply Class in front of it before it identifies one stock number.
Are the dashes part of the NSN?
No. 5340-01-165-7717 and 5340011657717 are the same number. Dashes only mark the FSC, the National Codification Bureau code, and the rest of the NIIN.
Last verified 2026-10-22 · Author FedOpp
Sources
Practical notes, not legal advice. The solicitation controls.