I bought three of these bits to use with my Milwaukee 3/8" hammer drill to drill a drainage hole in my 11" thick concrete and mortar brick garage wall. It took about 5 minutes to drill a hole about 5 inches into wall and the bit wouldn't go any farther. Thinking I may have dulled the bit I used the next two bits and tried for another 10 minutes and couldn't penetrate any further. I didn't get any shavings from rebar or anything, just no penetration. Thinking I hit a bluestone I gave up. My neighbor saw I was having a problem and I asked him if he had a drill and a long bit that he could try. He went through my hole and drilled another 6 inches inches into the wall in about 3 minutes.