The third member of Mach Storm, Sigma is older than RD, is rather cocky and argumentative, and tends to look down on RD. Despite this, he is a capable pilot. He usually provides fire support for the team with his Boldguard, whose cannons have been modified to fire various weapons (including the 'capture rings' used to immoblise wild Zoids). After the Boldguard was destroyed, it was replaced with a new Leostriker.

Later in the series, Sigma and Helmut's Zoids gain the ability to fuse into the Command Striker. For some reason, the Command Striker was never utilized in the final battle against Alpha. One has to wonder if the Command Striker could have held out longer against the Berserk Seismo's Sword Rail Cannon than the two Zoids separately.

[Source: Wikipedia]