The front of the welder is where you'll find the on/off switch and controls. In the upper-left-hand corner, there's a dial marked wire speed. This dial controls the rate at which wire is fed into the gun. The dial on the right is marked voltage, and it controls the amount of voltage coming from the welder. The more voltage applied, the hotter the arc coming out of the gun will be, and the thicker the weld will penetrate into the material. There is a direct correlation between voltage and wire speed: The hotter the weld, the quicker the wire must be fed into the puddle.