Gray Cerakote finish black composite stock chrome plated barrel aluminum alloy receiver gas operated Active Valve system inflex recoil pad LOP spacers large cocking handle reversible safety - Built on success. The SX4 is built on the bulletproof Active Valve system that was the core foundation of the SX3. We built on that solid operating mechanism and improved the balance controls and internal operating components of the SX4 to make it a worthy successor to the SX3. - RECEIVER