The Magpul STR (Storage/Type Restricted) is a drop-in replacement buttstock for AR15/M4 carbines using mil-spec sized receiver extension tubes. A storage-capable version of the CTR the STR has improved cheek weld and two water resistant battery tubes on a compact reinforced polymer A-frame design. The STR incorporates two integral sling loops a reversible push-button QD sling mount and a replaceable 0.30″ thick rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear.