The idea is fantastic, but the technology is seriously flawed. I was at work and the first hole I drilled in the bottom of the fiberglass tub worked great. pressed the magic button, pulled back the hole saw and simply removed the plug. After drilling a second hole, he stopped halfway. pulled the drill out, but the drill had no bite. here the bite seems to have pressed into the sleeve of the second part of the bite. Part of the bite, made with a drill, fell into the bowels of the house, and no one else saw it. I am returning all parts of 3 orders of this poorly designed saw and bit. :^(