The M6 is a Tier VI American Heavy Tank.
Essentially, a T1 Heavy uptiered to tier VI.
Because this tank still retains the same armor, this tank is downgraded into the Second-Line supporter. The armor is no longer effective as it is at its tier. However, it boasts some serious armament. At the top: a 90mm gun that is rather powerful at its tier. It can pretty much go through most tanks at its tier. Add with that, this gun carrier over to the T29, which is highly advised to research, because the 76mm gun that carries over is too insufficient to punch through common targets at its tier.