Magpul

-Mounts on mil-spec sized carbine receiver extension tube (not included) from manufacturers such asColt, LMT, Ruger, S&W, SIG, and others (please see the note below)-Two water-resistant battery storage tubes located on the left & right sides of the stock -Each tube will store up to two (2) CR123A lithium or AA batteries -Tubes are accessible from the rear in any stock position via hand-removable, o-ringed rubber plugs that are waterproof to 10 meters-Sloping cheek weld combines a slim profile with user comfort-Dual-side release latch provides easy adjustment while remaining anti-snag-Premium chrome-silicon lock spring provides positive locking & long service life-Internal anti-rattle leaf spring minimizes wobble on receiver extension tube-Rubber butt-pad offers an anti-slip surface & increases impact protection-Rollover on the toe allows for easier shoulder transitions & better fit when using body armor-Compatible with Magpul ASAP®, ASAP® QD, & other receiver-mount sling attachments-Sling Mounts -Rear -Integral push-button QD swivel sling mount accommodates up to 1.5" swivels (ambidextrous) -Rear/Bottom - 1.25" sling loopNote: There are two basic sizes of M4 Carbine receiver extensions (buffer tubes): mil-spec & commercial-spec. The MOE SL-S will only fit the common mil-spec tube.