Magpul Industries MOE Slim Line Carbine Stock, Fits AR-15, Mil-Spec, Gray MAG347-GRY 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.