Gigaton Arm

Gigaton Arm is Robo's 10th Mechanical Arm in Chrono Trigger. It sells for 12,000 G.

Etymology

As a megaton is a measure of the explosive power of one million tons of TNT, a gigaton (prefix giga- one billion) would represent the force of one billion tons of TNT. This would certainly match the arm's description of "dealing a mighty wallop".