The Magpul STR (Storage/Type Restricted) is a drop-in replacement butt stock for AR15/M16 carbines. 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. A shielded operation lever and supplemental friction locking system prevent accidental operation and minimize excessive stock movement for enhanced weapon stability and accuracy. The STR incorporates two integral sling loops, a reversible push-button QD sling mount, and a replaceable 0.30 rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear.