Ergonomic cheek rest with two storage compartments for M16/AR15/M4 butt stock. Greatly increases the cheek support while shooting. Significantly improves the cheek and head stability while aiming and shooting - eliminates the typical head movement and fatigue associated with sighting in targets for extended periods. Faster target acquisition and stay on target. Can store up to six CR123 batteries. Can store cleaning materials and other small gun parts. Waterproofed. Lightweight. Suitable for butt stocks manufactured by Colt Bushmaster Tapco Rockriver Arms Armalite Colt Canada and many more. Lifetime warranty. Available in the following colors: Black Tan OD Green.UPC: 676315005902