The Superlative Arms direct impingement bolt carrier is made from 8620 steel featuring a chrome lined bore (as per mil spec) with enhanced machining and a superior Diamond-like Coating; offering greater lubricity, less friction, and easier cleaning. To top off the carrier, they mounted a DLC gas key using OCKS (Optimized Carrier Key Screws) by Ned Christiansen resulting in the best possible staking and screw retention. Superlative Arms manufactures all carriers in-house to meet or exceed mil-spec. The Superlative Arms bolt carrier is compatible with all AR-15 bolts and this kit gives the end-user the freedom to choose their own bolt to match their preferred cartridge. Note: The Superlative Arms carrier does not come with a Bolt Assembly (bolt, cam pin, firing pin, or firing pin retainer). Bolt Assembly sold separately. FeaturesBolt Carrier Material: 8620 SteelBolt Carrier Finish: Chrome-lined, Dark DLC (Diamond-like Coating)Carrier Key Material: 4130 SteelCarrier Key Finish: Chrome-...