I think the one I got was for electrical conduit which I think makes a difference. the punch had 1 1/4" written on it, but it also had 1.71" written on it so I think the conduit punches punch a bigger hole so you can install a rubber grommit with in ID of 1 1/4". I'm assuming this anyway.
Long story short, I ended up with a 1.71" hole in a kettle that was supposed to be 1.25". it was a major major piss off to say the least.