Ordered these bits to cut a hole in the tile for the shower screen. As another customer mentioned, bits don't last long, but even for one-time use, you can't beat the price. I only bought 1 bit from a store twice the price but I had to return it because it didn't fit. Instead, I ordered this set of 15 sizes. I "sacrificed" a few small ones for practice that I knew I wouldn't need and also to start carving - I didn't know how long they would last. Once I felt confident I used the largest size (I needed) and it cut the perfect hole. It took some practice and I was glad I had extra bits to practice with. I used the size needed, donated a few in the process, and have a few sizes left for another project. Not a bad deal.