National Stock Number Assignment Process Server

National Stock Number (NSN)

In order to manage the huge number of individual items of supply that are bought, stocked, stored, issued, and used by the U.S. military, an inventory numbering system was essential. In World War II each branch of the services had their own system, the Army and Navy as well as individual departments such as Medical Department or Quartermaster. It was common to find a different name applied to the same item. It could be hard to locate supplies and harder to share.

Data plate for M-151A2 Truck, 1/4 ton, 4x4 (jeep)
showing NSN 2320-00-177-9258 upper right.

History of the U.S. Government National Stock Number (NSN)

Experience in World War II showed that it was unworkable for each service to have its own part numbering system. Even within one service, a variety of manufacturers’ item names for identical parts created inconsistencies in the various logistics management systems, making it difficult to control inventories. A common language of supply was needed to manage the growing complexity.

As part of the post-war reorganization that created the Department of Defense (DoD), in July of 1947, the Army-Navy Munitions Board established the Cataloging Agency to manage a single DoD resource called the Joint Army-Navy Catalog System. In 1949, the Federal Stock Number (FSN) system was established with an eleven digit number and the first FSN was assigned. On 1 July 1952, the Defense Cataloging and Standardization Act mandated a single catalog system for DoD. In 1958, the Armed Forces Supply Support Center (AFSSC) was established in Washington, DC, to maintain the Federal Catalog System and standardize item names used by the military services. When the Defense Supply Agency was created on 1 January 1962, the AFSSC was renamed the Defense Logistics Service Center, becoming the central control point for the Federal Catalog System. The Defense Logistics Service Center was later renamed the Defense Logistics Information Service (DLIS). A major upgrade to the catalog system occurred in 1975 with the implementation of the Defense Integrated Data System. The main change was the expansion of the eleven digit FSN to the thirteen digit National Stock Number (NSN), by adding a two digit NATO country code (see below).

Assigning National Stock Numbers (NSNs)

The Defense Logistics Information Service (DLIS) at the Battle Creek Federal Center in Michigan performs NSN assignments, initiated whenever a new item is ordered repeatedly, or when a new weapons system is built and put into service. Each NSN that is assigned to an item is the result of a careful review process called cataloging. All U.S. military services, as well as NATO and allied countries, submit cataloging requests to DLIS for processing. The information is held in the Federal Logistics Information System (FLIS) managed by DLIS in Battle Creek. DLIS operates within the Defense Logistics Agency (DLA) and is the only organization that is authorized to assign NSNs.

National Stock Numbers are assigned based on the end use of the item and cover everything from large, complex items like a weapon or truck to tiny individual components. As of 2005, there were about 14 million active and inactive NSNs in the FLIS.

Some examples of actual NSNs:

Structure of the National Stock Number (NSN)

The configuration of the NSN is a 13-digit number, as the examples above show. It is composed of these overlapping sub-groups:

  • Federal Supply Group (FSG): Positions 1-2
  • Federal Supply Class (FSC): Positions 1-4
  • NATO Country Code: Positions 5-6
  • National Item Identification Number (NIIN): Positions 5-13
  • Serial Number: Positions 7-13

The first two digit positions identify the Federal Supply Group (FSG), the broad category in which the item belongs. For the HMMWV or M-151A2, the FSG is 23, defined as:

  • FSG 23: Ground Effect Vehicles, Motor Vehicles, Trailers, and Cycles

The FSG is followed by two additional positions which together with the FSG form the four position Federal Supply Class (FSC). The FSC narrows the category down to something more specific. In the case of the HMMWV or M-151A2, the FSC is 2320, defined as:

  • FSC 2320: Trucks and Truck Tractors, Wheeled

The last 9 positions (e.g. 01-371-9577) are the National Item Identification Number (NIIN) and identify the specific item. The first two positions of the NIIN identify the NATO country code for the country making the number assignment. The codes 00 and 01 are used by the United States. The last seven digits of the NIIN are the item serial number. The serial number does not follow an assignment pattern as the FSG, FSC and country code do; it is merely a number chosen for the item.

When the FSN was converted to the NSN in 1975, existing FSNs were typically changed over by simply adding "00" between the FSC and the serial number. For example, "First Aid Kit, General Purpose, Rigid Case", FSN 6545-922-1200, was changed to NSN 6545-00-922-1200.

If an item is issued in different sizes, each size will have its own NIIN. Sometimes all the sizes follow a logical pattern, sometimes not. When items from different manufacturers perform the same function, have the same characteristics, and are the same size, a single NSN may be assigned. For example, all flashlight standard Alkaline D-cell batteries have the same NSN regardless of supplier (6135-00-835-7210).

Because the FSC is assigned based on end use, it is possible for the same item to be in more than one FSC. For example, a cleaning compound could be assigned FSC 6850 when used for general purpose cleaning, but the same chemical composition would be assigned FSC 6750 when used as a photographic cleaner. In each case, the NIIN would be different.

Variations in the National Stock Number (NSN)

When an NSN is assigned to an item, that reflects the situation at a particular point in time. Later, different specifications or suppliers, usage changes, or just bureaucratic shuffling may result in a new NSN being assigned to the same or a very similar item. This can be confusing, especially if the change is merely one of nomenclature with little or no change to the physical item. It means that you have to be cautious in the use of NSNs, especially for items from the past where it may be difficult to discover all the relationships that may have been in play when the item was originally developed, tested, procured, and fed through the military logistics system. If you find an NSN referenced in print or on a web page, be aware that it may not be the only NSN that applies to the item. If the item has to fit with something else (like a set of poles for a tent) then the exact, correct NSN may depend on the NSN of the related item it has to fit with.

For example, the Improved Rain Suit went through a number of minor design changes plus color changes from olive drab to camouflage pattern resulting in a series of NSNs being assigned, as shown in a table on the linked page. If you are looking for an Improved Rain Suit in surplus channels, any of the NSNs may be used depending on the date, model, color and size details. If you are ordering one through military supply channels, then be careful to use the most current, actively supported NSN that applies to the authorized item.

Changing NSNs are announced through military publications, but its very time consuming to keep up. PS Magazine tries to help, as in the example to the right.

Today in WW II: 9 Mar 1945 279 B-29 Superfortress bombers ignite a firestorm in Tokyo, destroying 267,000 buildings, creating 1 million Japanese homeless [Mar 9-10].   
M-998A1 HMMWV2320-01-371-9577
M-151A2 Jeep (data plate in top photo)2320-00-177-9258
Bandage Kit, Elastic: 4 inch6510-01-460-0849
Marine Corps Combat Boot, Hot Weather: size 11N8430-01-483-0027
Coat, Day, Rip Stop, 3 color desert: size S-R8415-01-327-5302

What are National Stock Numbers (NSN)?

A National Stock Number is a unique identifying number applied to an item that is repeatedly bought, issued, and used throughout the federal supply system.  According to the Defense Logistics Agency, NSNs are used to identify and manage nearly every imaginable item, from aircraft parts to  light bulbs.  NSNs are an essential part of the military’s logistics supply chain.

Why are NSNs important for Foreign Military Sales (FMS)?

The FMS process is used to allow foreign customers to procure standard USG items.  An item is considered “standard” military equipment when it is assigned a National Stock Number.  Seeking to register products with an NSN is thus an important first step in an FMS sales strategy.

The NSN is officially recognized by the United States Government, the North Atlantic Treaty Organization (NATO), and many governments around the world. Federal agencies, including the Department of Defense (DoD), use the NSN to buy and manage billions of dollars’ worth of supplies each year. The Federal Logistics Information System (FLIS) catalog currently contains about 14 million U.S. NSNs. In addition, non-U.S.NATO members hold approximately eight million active NSNs that are assigned to items produced in their countries.

For Foreign Military Sales purposes, the NSN provides a unique identifying number for each piece of equipment.  Although non-cataloged items (items without an NSN) can be occasionally purchased through FMS, the DoD acquisition system and the FMS procurement process rely heavily on NSNs.  Foreign Customers may request a specific item by NSN, ensuring that the DoD procures exactly what they want.  For U.S defense companies, having their products catalogued with NSNs becomes a strong competitive advantage for international arms sales under FMS.

How do items get assigned an NSN?

The DLA Logistics Information Service assigns all NSNs through a review process known as cataloging. Requests for NSNs are initiated whenever an item is repeatedly ordered or when a new weapons system is being developed. The U.S. military, government agency, or NATO country may submit a catalogue request when they identify a need for a specific item. Manufacturers and suppliers may not request a NSN.

How can Defense Companies get their products catalogued with an NSN?

While manufacturers cannot directly request an NSN, they can – and should – be vigilant to ensure that their products are catalogued. Effectively, in order to get a product catalogued, the company needs to sell it to the government.  Once they make that first sale, the company should follow-up to make sure that their case manager submits an NSN request for the product.  Companies can check on DLA’s website to see whether their product has a pending catalogue request.  If not, the company should ask their case manager to submit one (and should provide any necessary information as well).

For a great reference on National Stock Numbers, see the Defense Logistic Agency’s NSN information booklet (pdf file).


What other questions do you have about National Stock Numbers?  What is your experience in getting catalogued?

Read more in my series on military exports:
What is FMF?
What is ITAR Restricted?


Filed Under: Defense Exports GuideTagged With: National Stock Numbers, NSN

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