Troy Quick Attach Picatinny Rail Section with QD Swivel Hole, Fits Certain TROY Rail Systems including TRX 308, TROY HK, TRX Extreme, Alpha and Delta Rails, and T-22 Sport Chassis, M7 Uppers and M7 Kit, Delta Rails, Secures with 2 screws, 4.2", Black Finish SRAI-TRX-P4BT-00