The Aero Precision M4E1 Complete Lower Receiver with Magpul SL Carbine Stock is the perfect upgrade for your AR build. This complete lower features an M4E1 Lower and is upgraded to include an Magpul PRS Lite Stock. The MOE SL® Stock – Mil-Spec Model (MOE Slim Line) is a drop-in replacement buttstock for AR15/M4 carbines using mil-spec sized receiver extension tubes. Designed for the modern battlefield, the sleek profile, dual-side release latches, rolled toe, and angled rubber butt-pad are optimized for use with body armor or modular gear and provides for efficient shoulder transitions.