Black oxide drill bits for longer life and faster drilling. Very high quality masonery drill bits. Great for drilling concrete, masonry, lightweight block and stone. Masonry drill bits for occasional use do not have to live up to the daily pressure in the same way that choices for professional use require. Masonry drill bit sets are popular choices for those who work in this type of profession because the sets give users a wider array of options which makes carrying multiple tool sets less cumbersome. I bought this hammer drill bit set and used it for the first time yesterday. Drilled a small and clean cut hole down to my basement for me & my roommates ethernet cables. I could smell insullation burning and the bit kept slipping in the chuck. I knew it would require drilling about 30 holes 4-inches deep into the pool concrete and didn’t want one bit to get dull on me. We bought this to drill one hole through roughly 12 inches of concrete block, mortar, and concrete. We had a little hiccup at first because our drill wasn’t powerful enough, but once we swapped out the drill, we had no problem. I had a steel dragon bit that self-destructed in the same material when the teeth debonded form the drill barrel. Do yourself a favor and get the bluerock drill instead of the steel dragon drill. The steel dragon drill is only one speed and doesn’t have a safety clutch, when the tooth broke loose from my first diamond core drill the drill body spun around and nearly broke my arm. I just made my own by using a 1 1/4″ bolt and a hardened 1/2″ bolt. It bent a little on me, too (twice) but was easy to straighten out in a vise. Core drilling in sidewalks 4″-5″ thick. Never drilled glass before; got great results from this! It worked great to drill trough my exterior brick wall. It fit a 3/4 inch piece of pvc nice and snug so that all of the wires are protected. The sizes are perfect for a smaller set and include two of each of some of the most used sizes. I just wanted to add a 5 star review to the list. These drill bits did not live up to my expectations. I had to drill four 5/32 holes in regular household masonry. First hole only went in about 1″ before it stopped cutting. The problem is, he always has all of the tools with him. I have a few bits, but this kit seemed like the perfect set to have with my drill. These rocks are about 30x60x36 inches. Used this for drilling hole in boulders to split them. I wish it did last longer hence 4 stars. Having more bits and only drilling 1 hole per bit to keep them cool and then wait till they are cool extends the life. Also hit the right speed they last longer than going fast.