Diamond Bit Set is excellent for precision cutting fiberglass shower enclosures for installing valves and showerheads. You don't want to risk the edge breaking or cracking with other bits, especially those used for wood or metal. The kit is good, it included instructions for stability and accurate hole cutting. The product was also delivered very quickly and on time. The product matches the ad but does not come with a kit case which is fine as I have an old ammo case that asked to be used for something.