The SBA4 Brace and Buffer Kit combines the ever popular SBA4 Brace with a true Mil-Spec Buffer Kit. You know you're getting quality with the SBA4 plus you can be confident that you're fitting it on a true mil-spec 7075-T6 Buffer Tube with a chrome silicon buffer spring and a properly weighted carbine buffer. Even the end plate and castle nut are sourced from the best suppliers. No weak links to be found in this kit. Plus you're backed by the AR15Discounts.com Satisfaction Guarantee.The SBA5 is ATF approved for use on AR pistol builds.Includes: Mil-Spec Carbine Buffer Tube / Receiver Extension 6 Position 7075-T6 Aircraft Grade Aluminum Hard Anodized Carbine Buffer Spring Castle Nut/Receiver Nut Mil-Spec Receiver End Plate Carbine Recoil Buffer