I used this bit for about 7 minutes and it was completely destroyed. I drilled a 65mm hole in 2" x 8" and 2 of the 4 carbide drill bits broke off (500rpm). Remember I still have to go through the 4 inch brick. Well, I made a groove in brick and that was the end of the tool's useful life. I'm so angry now because it took 30 minutes of work with this drill bit to 2 hours of manual labor to chisel the hole and it's nowhere near as neat and clean as using a bit. I wouldn't recommend this at all except for scrap. If I could give it 0 stars I would.