The patented Magpul ACS (Adaptable Carbine/Storage) – Mil-Spec Model is a drop-in replacement buttstock for AR15/M16 carbines using mil-spec sized receiver extension tubes. A streamlined, anti-snag profile shields the release latch to prevent accidental activation. Similar to the Magpul CTR®, the ACS also features a supplemental friction lock system that minimizes excessive stock movement for enhanced weapon stability and accuracy*. Dual, rear accessible, water-resistant battery storage tubes and an integral storage compartment in the butt of the stock provides multiple storage options. The ACS comes standard with a 0.30" thick rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear. Made in U.S.A.