They were a replacement for a Wen 7 bit set which actually only had 6 different bit sizes and some of them had one dangerous amount well this set is far from the best the design and finish of the cut surface is rough leaving a bit of a crack at the bottom of the hole but the holes are nice and round and this set was compared to the "pro" quite cheap " set. For one-time use by a home master, I find them almost perfect.