FAB Defense GLR 16 AR15 / M16 Buttstock With Battery Storage - Black - The GLR-16 Buttstock for your AR15/M16 provides you with enhanced versatility with it's stock extension and optional adjustable Cheek Rest. Features Uniquely designed rubber butt pad for fast and stable shoulder positioning; Unique patented "Anti-Rattle" mechanism, fits perfectly on MIL-SPEC and commercial after-market buffer tubes; Three Integrated Slots for Sling Attachment, One in the Front and Two at the Rear; Two Ambidextrous Metal Quick Release Rear Sling Mount Points; Water-resistant anti rattle storage compartment for two CR123 or AA batteries; Maintains Contour & Size of Original Design; Made from fiberglass reinforced polymer composite;