I returned it. I was doing a drywall project in my basement and didn't want to spend money on a special drill press. This thing worked well if you had a high speed drill. It was only good a small percentage of the time. This forced me to use a standard PH#2 bit to push the screws even further. It was also a frustrating task until I grabbed my "Hard Mark" drum beats. Doesn't matter. I don't know what it is, maybe a black coating but they really hold the screw. So much so that I brought this part back and just used this simple bit for easy screwing in and countersinking at low speed. The hard bit just REALLY holds the screw. almost never comes out.