GR16 Carbine Plastic Receiver Material: Nylon/Fiber Magazine: 450 Rounds Handguard/Grip: Nylon/Fiber Stock: Nylon/Fiber Gear Box material: Zinc Gear set material: Steel Bushing Material: Brass Hop-up Chamber: Plastic Motor: 25000 rpm Hi-torque Piston Nylon/Fiber Inner Barrel Length 357 mm Inner Barrel Internal Diameter: 6.04 mm Muzzle Velocity:90-100 m/sec w/0.2g BB Fits this gun/guns BATTERY AND CHARGER NOT INCLUDED Please use .20 gram high quality BBs or heavier with this gun. Using lighter ammunition with this gun will void the warranty. We recommend: .20 gram high quality BBs.