are perfect for my jet drill if you want to buy one of these get this style with coolant feed I use antifreeze at the moment my coolant is coming don't go here, largest size so far is 1-1/2" to 1/2" AR 50 plate, perfect hole every time, doesn't get hot like drill bits, I make 4" shims for Galion Grader 1963 to fit the To hold blade to machine Shame I wouldn't have found this setup a few years ago, saves a lot of time when you're drilling a lot of holes in steel.