F Strike Industries Pistol Buffer Tube/Short Receiver Extension Kit, AR-15, 5.28 in, Black, One Size, SI-AR-SPRE-SLICK-BK $52.95 SIARSPRESLICKBK show more like this Free Shipping on most orders over $49 Optics Planet F Strike Industries AR-15 Pistol Buffer Tube Kit - Black $54.95 SI-AR-SPRE-SLICK-BK show more like this Calculated in Cart Primary Arms F Strike Industries Short Pistol Receiver Extension Buffer Tube Kit AR-15 - 766956 $66.95 SI-AR-SPRE-SLICK-BK show more like this 5.00 MidwayUSA F Strike Industries Pistol Buffer Tube QD Connection Flat Wire Spring 7075-T6 Aluminum Black SI-AR-SPRE-SLICK-BK $72.79 ARSPRESLICKBK show more like this $10 Flat for Firearms Cheaper Than Dirt