I expected cheap diamond drill bits and that's what I got. I had to drill fifteen 3/16" holes in very hard stoneware, and I figured if I drilled at low speed with a corded Milwaukee Magnum drill and lots of water, I could do it. Almost there. They lost the diamonds pretty quickly. , if the diamond coating has fallen off, the bits are bent, etc. Not surprisingly, the cost of each of them is 0.61 cents. I bought a DeWalt diamond drill bit as a replacement. good to go Through all my years of using