I have been using this type of drill for many years. I am an electrician and have tried many things. This drill bit cuts through the toughest wood with little to no effort. In the new design, you simply turn the screw and then only hold the drill. The beat does the rest. After a few nails, you can pretty easily sharpen the bit with a hand file. I only had to replace a little when one was on site; never, for he will eat no more wood. This is not a bit to use with a small drill, so don't try it unless you plan to buy drills. Vermont used to or maybe still sells something similar. I used to ask about these and called them butterfly pieces. Although I haven't seen her for a long time. These were two-bladed chisels with a self-launching propeller. They worked well and were a lot cheaper than the Milwaukee, but they also wore out a lot quicker. Good product in every respect.