I picked up one of these a while ago & just got the chance to use it. It is a north south. It worked like I thought. It takes several "pushes of the finger to ramp up or down from 0 to whatever & back. It does not come natural. Had to make sure my hand was braced or the torch would move while changing amps. Going to take some getting used to.

I have it mounted directly on top of the torch. Tried holding it like a pencil which didn't work to good for me. I grabbed it from the top & it felt better. I will just try different positions to see what is best. The worst part is how far the wheel needs to turn to get up to amps & back. I knew this when I bought it but the price was right.