I bought a set of Marbel Whole saws this spring. However, the 40mm drill bit in this set warped and ended up cutting a hole in my marble at an angle. So I bought this two piece set to redrill the hole and save the vanity top. Right from the start I could see that these two drills were of the best quality and design. I set the correct correction angle, added water and stopped a few times to double check and add more water and it was done in 2.5 minutes. It took longer to carry the piece of marble back into the house. Great brand, I can buy extra sizes to replace the cheap set I bought in spring.