I needed to drill perfectly round holes in a ceramic wall in my shower. I looked up Revain and found these diamond hole saws. They are not expensive so I bought several different sizes. They work great, got the job done quickly with professional results. In this regard, I strongly recommend that you also purchase a Drilax hole saw guide. These hole saws don't have a center drill bit like a regular hole saw, so they will go around your tile if you try to cut them free hand and break the tile. The guide attaches with a large suction cup and holds the hole saw in place until you're ready to go. You also have to use water to cool the saw blade, so it's really a two person job. I've also used a cordless drill, standing in a puddle of water and having the drill plugged into 110 volts seemed like a bad idea.