With the unfortunate news of Anderson Manufacuring closing its doors, we will not be able to warranty or exchange any items directly through them. These items are not returnable.The Anderson Pistol Buffer Tube is compatible with the AR15 platform. It can be used with a carbine length spring and buffer, and works with standard endplates and castle nuts. You can use this item for your next AR15 pistol build, or as a pistol brace tube for other platforms like the Grand Power Stribog, or Kriss Vector Pistol. This is an AR15 Pistol Extension, made From 7075 Aluminum, that will work with all Mil-Spec AR15 lower receivers.Anderson Pistol Buffer TubeMFR#: D2-K021-B000UPC: 640901517063