so far seems to be good bits I've used about 5 of them so far and they all so far have drilled through the stone unlike other bits on the market that don't have the coating on the flat tip shipping was super fast and great customer service!
at first I didn't think they would drill cause I didn't feel any grit on the tip but then i tried and I haven't had a bad bit yet they all drill. unlike some I got off Amazon from a reputable company that didn't do anything. these are good for making a hole or enlarging a hole that is already drilled. I will get more next time the price is amazing on these. u have to push down a bit hard to get it to drill down but they work. I suggest start at the front and drill to the back in case you bust out the other side from pushing. over all a good product and they arrived in the USA relatively fast even with the virus.
all ok!