The American Defense AD-170-S is a quick-release picatinny-style rail adaptor, shorter than the AD-170 mount. Constructed of durable 6061 T6 Aluminum and finished with a T3 Mil-spec anodizing. The QD Auto Lock lever system adjusts to accommodate in-spec and out-of-spec rails. Mount base will accept all VPG bolt-on rails (3 ?lug and 5-lug). The rail adaptor allows users to add a quick detach lever mounts to standard bolt on accessories. The AD-170-S riser base also works with Atlas Bipods.