LOW MASS COMPLETE BCG W/ ADJUSTABLE GAS KEY Already on the 3 gun scene in the pro shooters gun-s RCAs Low Mass carrier group is in high demand. NOW AVAILABLE WITH RCAs patent pending. Adjustable Gas Key to slow down your lightweight system. Made from 8620 steel and finished with H&Ms Blacknitride+ treatment this carrier is lighter than the standard M16 carrier. Weighing in at just over 8.9 ounces the RCA competition carrier makes a noticeable difference. Carrier comes with Nitrided 17-4 stainless firing pin and our enhanced 9310 nitrided bolt. Includes: Instructions, 3 1/8 screws and 2 3/16 set screws and wrench included to make necessary adjustments.