Gerry of OddysAirsoft goes over the Umarex HK45 Gas Blowback Pistol made by KWA... "The classic Heckler & Koch large calibre airsoft gun with Polymer body and metal slide and with full HK trademarks this makes for a truly outstanding replica in both weight and feel. With Gas-Blowback-function of the metal slide, including a second back-handle for replacement."