Strike Industries drop-in replacement buttstock for your AR/15/M16 carbine uses mil-spec sized receiver extension tubes. The Viper stock integrates features sought by military professionals and firearms enthusiasts around the world.Strike Industries drop-in replacement buttstock for AR-15 /M16 carbine using Mil-Spec sized receiver extension tubes. The MOD1 stock integrates features sought by military professionals and firearms enthusiasts around the world. Strike Industries came up with a lighter, compact buttstock, at an even more attractive price point. Features: Slide on replacement for factory collapsible butt stock QD sling mounting points integrated on both sides in positions for optimum usage Enhanced cheek weld Easy to replace and quick to install Designed for use with and without rubber buttpad