Replacement pistol-grip for some AR10-type weapons; Removable and replaceable front and rear straps for a custom fit over multiple hand sizes; Improved ergonomics and positive anti-slip texture on both sides and rear back-strap; Removable inner core holds a reusable 1/2 fl oz. lubrication bottle (oil not included); Custom waterproof storage of batteries (AA/AAA or CR123A) or spare bolt/firing pin (AR15/M4) is available with optional Storage Cores; Each kit includes three backstrap sizes (S,M,L), two frontstraps (A1 and A2 style), lubrication bottle core, and dual-drive mounting screw