This dry/wet hole saw is what you need for cutting holes in sanitary tile in new or existing floors or walls. There is no central pilot drill, therefore the use of a pre-drilled template/pilot hole cut in plywood or other material is recommended.Cuts wet or dry but highly recommended wet as dry cutting generates a lot of dust.Will fall apart Like cheap diamond coated bits, cut a hole and the diamond material disappears.Can be used as a flat crown it cuts so well.I tried it on cement and had no problem cutting quickly and smoothly.If you have used cheaper bits in the past you will be amazed at how well it cuts and how reliable this bit is when cutting holes you need an adapter Buy to use this bit, but the best news is that the same adapter will fit many other sizes of Toolocity bits. Thanks to Revain and Toolcity for another great product.