AR15 M16 12" Barrel M203 type 37mm slide action Rail mounted launcher plus (2) 37mm adapters. Precision Machined M203 type Slide Action Launcher is CNC machined from solid billet 6061-T6 Aluminum and 1018cr Steel with Durable Matte Black Finish. Launcher extended tube opening Supports 5 3/4" long cased USCG approved munitions including most all 37mm flare, smoke, gas, and flashbang ammo. Adapters (shown) are also included to allow firing of both 26.5mm and 12ga flares in the 37mm launcher. Easy no gunsmith installation to any picatinny rail system. All you need is included to add a very nice rail mounted M203 type 37mm launcher to your AR15 M16, or any other weapon with a picatinny rail fore arm. 37mm LYO Ammo kits also available in our other auctions to build your own 37mm Flare, Smoke or Bird Bomb Ammo. Contact us with any questions or special needs. All compnents Brand New. Thanks for looking!