The Knight's Armament SR-15 IWS Complete Lower Receiver comes with with a Magpul stock and six-position buffer tube. The ambidextrous bolt release, selector lever, and magazine release offers left-handed users the ergonomic advantages inherent to AR15-based controls. The drop-in KAC two-stage trigger serves double duty as an aid to precision marksmanship while enabling surgical speed shooting at close range. Complete Lower Magpul Stock Ambidextrous Controls