The KAK K-SPEC AR15 Bolt Carrier Group features a low mass design with satin gold anodized aluminum carrier optimized for mid-length and rifle-length gas systems.KAK K-SPEC AR15 Bolt Carrier Group for 5.56/.223Low mass BCG design for reduced reciprocating weight9310 dual ejector bolt with NP3 cam pin coatingAluminum carrier with satin gold anodize (Mil-Spec buffer anodize color)Down vent design for enhanced performanceRecommended for mid-length rifle-length or similar gas systemsThis BCG is considered a consumable part and performs best in ARs with properly tuned gas and buffer systems. Not recommended for hard use applications.