Review on 545 Diamond Cutting Wheel Set (22mm) - 25pcs with 402 Mandrel (3mm) - 5pcs and Screwdriver: Ideal for Rotary Tools by Eric Owens

I cut holes for sockets in porcelain stoneware. They make a nice clean cut but either take a long time or require many blades. I used to use diamond tools made in China. I was very frustrated with hole saws until I realized that they need to be turned as slowly as possible, filled with water and operated with light pressure. If you do, they'll last a long time and cut well, albeit slowly. They can move faster or lean harder and slice faster, but that will burn them. I have ordered more of these. To use them I have to stand there for 30 minutes holding my heavy drill in place. I'd rather burn them out quick, so I push harder and spin faster and it wears them out, but that's okay.