LWRC International's UCIW (Ultra-Compact Individual Weapon) stock system shortens the overall length of the firearm by a full inch, as compared to a standard AR. The kit includes the stock, receiver extension, index plate, buffer, recoil spring and castle nut. Its components were designed to work together and should be installed together for reliable performance. This stock is lightweight and features integral sling attachment points, easy one-hand adjustments and excellent cheekweld. The rubber buttpad prevents slippage during firing. Its receiver extension has four positions to adjust the length of pull. Derived from our UCIW project, it is a great option for shortening the overall length of your rifle.