Mounts on mil-spec sized carbine receiver extension tube (not included) from manufacturers such as Colt, LMT, Ruger, S&W, SIG, and others; Supplemental friction lock minimizes accuracy robbing wobble*; Sloping cheek weld combines a slim profile with user comfort; Shielded release latch prevents snagging and accidental operation; Premium chrome-silicon lock spring provides positive locking and long service life; Side mounting slots accept optional cheek risers for NON-AR15/M16 applications; Removable 0.30" Rubber Butt-Pad offers an anti-slip surface and increases impact protection; Compatible with Magpul ASAP and other receiver-mount sling attachments