Ordered a 2"-4"-6" Core Bits. They are well worth the purchase price. 4" Bit Cored 8" Concrete (hard stuff) just as well as bits 3 times the price. Have not used the 6" yet but expect it to perform well also. The 2" Bit on the other-hand had a hard time. Drilled 10+ holes with it and the core kept breaking inside the bit causing me to stop and fish out a 1-2" piece of concrete every few minutes. I don't think the 2" Bit was Uniform in circumference and that's why it kept breaking the core off inside of it. Turned a 2 hour Task into a several Hour Task and a Mess to clean Up at that. Would I recommend these Bits. YES! I think I just got a bad 2" Bit. The 4" Bit cut through with ease. Well Worth the Money and I'll be buying more.