I was willing to give them a bad review. I took a lot of trouble drilling a hole in the basement wall. These things just didn't fit. I needed 2 inches and it took 5 minutes to deepen 1/4 inch. It was uncomfortable. Another project required me to drill a hole in my porch to install an anchor for a new porch post. Cut through the cement as if it were hardwood. The difference is amazing. I think I would have thought the porch would be softer concrete, but I didn't think it would be that strong. I have a Ridgid cordless hammer drill. I think maybe for my basement I just needed a better drill press.