The Cobalt Kinetics Billet Upper Receiver features a proprietary ambidextrous rear actuated bolt release. It has been carefully designed and crafted from 6160-T6 aluminum with a durable anodized finish. It features a 7-inch M-LOK handguard with a full picatinny rail. This billet upper is just what your build needs for a rock-solid foundation and unwavering durability.