Magpul

-Mounts on commercial -spec sized carbine receiver extension tube (not included) from manufacturerssuch asBushmaster, DPMS, Olympic, and others (please see the note below)-Sloping cheek weld provides a wide contact surface for user comfort-Storage compartment in tail of stock with positive latching access foor on right hand side-Supplemental friction lock minimizes accuracy robbing wobble*-Premium chrome-silicon lock spring provides positive locking & long service life-Shielded release latch prevents snagging & accidental operation-Replaceable 0.30" Rubber Butt-Pad offers an anti-slip surface & increases impact protection-Compatible with Magpul ASAP®,ASAP® QD, & 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" sling loopNote: There are two basic sizes of M4 Carbine receiver extensions (buffer tubes): mil-spec & commercial-spec. If you have a commercial-spec extension on your rifle, make sure to order #MAG378* Friction lock performance may vary depending on the host receiver extension's dimensional tolerances.** Specifications based on extended-length (slant-back) commercial-spec carbine receiver extension & may vary depending on tube manufacturer.