The Magpul ACS (Adaptable Carbine/Storage) – Mil-Spec Model is a drop-in replacement buttstock for AR15/M4 carbines using mil-spec sized receiver extension tubes. Dual, rear accessible, water-resistant battery storage tubes and an integral storage compartment in the butt of the stock provides multiple storage options. Similar to the Magpul CTR®, the ACS also features an anti-snag release latch to prevent accidental activation along with a supplemental friction lock system that minimizes excessive stock movement for enhanced weapon stability and accuracy*. 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. FEATURES Mounts on mil-spec sized carbine receiver extension tube (not included) from manufacturers such as Colt, Armalite, S&W, LMT, and others (please see the note below) Sloping cheek weld provides a wide contact surface for user comfort Two water-resistant battery storage tubes located on the left and right sides of the stock Each tube will store up to three CR123 lithium or two AA batteries Tubes are accessible from the rear via a tethered, hand-removable rubber plug Storage compartment in tail of stock with positive latching access door on right hand side Supplemental friction lock minimizes accuracy robbing wobble* Shielded release latch prevents snagging and accidental operation Premium chrome-silicon lock spring provides positive locking and long service life Replaceable 0.30" Rubber Butt-Pad offers an anti-slip surface and increases impact protection Compatible with Magpul ASAP®, ASAP® QD, and other receiver-mount sling attachments Sling Mounts Mid – Included reversible Sling Mount Kit – TYPE 3 fits up to 1.5" push-button swivels (swivel not included) Rear/Bottom - 1.00" sling loop NOTE: There are two basic sizes of M4 Carbine receiver extensions (buffer tubes): mil-spec and commercial-spec. If you have a commercial-spec extension on your rifle, make sure to order the Commerical-Spec ACS. ITARInternational Traffic in Arms Regulations Controlled Product