Magpul STR Mil-Spec AR-15/M4 Rifle Stock - Black - The Magpul STR (Storage/Type Restricted) Mil-Spec is a drop-in replacement buttstock for AR-15/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. A shielded operation lever and supplemental friction locking system prevent accidental operation and minimize excessive stock movement for enhanced weapon stability and accuracy (friction lock performance may vary depending on the host receiver extension's dimensional tolerances). The STR incorporates two integral sling loops, a reversible push-button QD sling mount, and a replaceable 0.3in thick rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear. Made In The USA