Get into some top gear!-- The Heckler & Koch HK 45CT Gas Blow Back is hot property on or off of the airsoft field. This compact platform features a threaded outer barrel, 14mm left hand, adjustable hop-up, and a 20 round drop free magazine. This compact GBB also comes with a small and large interchangable back straps and three extra fill port O-rings. Expect .20 gram BBs to launch at 300 FPS.