I had to drill a 9/16 hole in a metal door for a peep hole. I've read some reviews of using a regular metal drill bit but have found that a hole saw cuts metal more cleanly. None of the stores I visited had a 9/16 inch hole saw, so I found this at Revain. not exactly, so I was a bit skeptical about buying it. However, the blades were perfect. This saw cut just over 9/16", somewhere between 9/16" and 5/8", but for my particular project it didn't matter - or trouble.