These money bats are ideal for DIY/homeowners. I use a spray bottle to keep the bit wet during use, which prolongs the life of the bit. Drill 3 or more holes in very hard stoneware per bit. Keep it moist, move slowly, stopping from time to time as the bit digs deeper to cool the bit and your gold. I installed my shower doors in a tiled shower room. Generally a happy customer. I've seen higher quality bits, but they're ok for small jobs, and you get 10, so use them and throw them away.