I only used the smallest drill bit, 5/32, to drill 5 holes in 3/8 thick marble tiles for flange mounting of the toilet (toilet). The racket looks the same and will not be damaged after use. Drilling was smoother and faster than the masonry bit I used to drill the first hole. The holes are perfect, the tile is not cracked or scratched. It is extremely important to use water for lubrication during drilling as prescribed. Starting the hole at a 45 degree angle, the drill did not roll. I stopped at