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. This Anderson MIL-SPEC Stock Hardware (Receiver Extension & Buffer) Kit includes an extruded 7075-T6 aluminum receiver extension (buffer tube) with a durable hardcoat anodized finish. It features an extended bottom lip reducing carrier tilt, the buffer tube is compatible with MIL-SPEC AR-15 stocks.This kit includes:6-position MIL-SPEC tubeCarbine recoil springCarbine recoil bufferEnd plateCastle nut