Sounds like a good set of bits. and assuming I base my comments on a bit. the largest in the set, a 12mm bit. I used a bit on a granite post to set the anchor. Apparently the granite is too hard because one of the "blades" at the tip broke off within 1 minute of starting drilling into the granite column. Judging by the description I thought they were working on granite. I will use them, just not on granite. The old adage "you get what you pay for” seems to apply here. They were inexpensive compared to carbide bits.