Beware, however, of the markings. Knockout punches (for conduit and the like) have size markings based on the ID of the conduit, not the OD of the fitting which goes through the punched hole. So one marked
5-1/2" would likely produce holes somewhat closer to 6" diameter. :-) Chassis punches, from the same maker (Greenlee) are sized to the diameter of the hole produced, but I've not seen them in that large a size. So come equipped to measure the punch diameter before you spend your money -- and those are *not* cheap. :-)Good Luck DoN.