Madbull BB launchers are high quality and affordable products. Constructed entirely from high grade aluminum for light weight and strength. Not like other B.B. grenade launchers, it will fit directly to all 20mm rails. Length = 155mm, Height = :65mm. Only uses Madbull M381 18 rounds Extreme Powerful BB Shower (6mm), Madbull M781 42 rounds Powerful BB Shower (8mm), Madbull M433 48 rounds Powerful BB Shower (6mm), Madbull M576 Hi-Power Soft Rubber Trainning Shell. It's small compact size means it will also fit on SMGs and long pistols! Designed to look a lot like the H&K launchers! Highly recommended. Barrel is completely removeable to make loading large capacity BB shower grenades possible.