Magpul Industries STR Stock, Fits AR-15, Mil-Spec, Black MAG470-BLK 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. 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" thick rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear. Made in the U.S.A.