A quick presentation by Umarex of their fully licensed HK45C Gas Blowback Pistol... "This fully licensed replica HK Airsoft pistol from Umarex and Elite Force is powered by green gas and is in 6 mm caliber. the all metal magazine holds 20 rounds of Airsoft BB's and green gas. It has a full metal slide with a polymer frame. This pistol sports an ambidextrous slide catch and magazine release, a on frame safety for de-cocking the hammer and making the gun safe.