I bought these to drill through the cement board of my side yard to secure my 10ft gate. I do NOT have a hammer drill and I figured it would take quite a bit of work and gradually increasing the size of the drill bit to get the required 1/2 hole diameter. I was wrong. Using my Milwaukee M18 FUEL Driver, I finished the hole in less than 20 seconds. I didn't even have to cool the racquet with water. I highly recommend these rocks. Can't comment on durability as I only had to drill one hole but the bit is still sharp and apart from some paint removal it looks like new.