The M6 was the first modern US heavy tank. This design had a single three-man turret, with a vertically-stabilized 76.2 mm gun. The turret was cast and had an electric drive and manual traverse. There was also a bow mount with twin cal.50 machine guns handled by the assistant driver. The vertical volute spring (VVSS) suspension was borrowed from the M3 Lee, but the tracks were doubled in width, with two rubber shoes instead of one. The entire side was protected by a large, one-piece side skirt. The armor ranged from 3.27 inches to 1.73 inches. The overall weight was a staggering 50+ tons.