2-1/2" Dry Diamond Core Bit for Brick and Block with 5/8"-11 Pilot Bit Adapter, 9.5" Drilling Depth, 5/8"-11 Arbor

In short, it works nicely. The core bit attached nicely to my hammer drill. Drilling in NON-hammer mode, the bit successfully cut through 12" of concrete reinforced block in the side of the home, which led to a successful 6" vent pipe installation for my exhaust hood. I did use it dry for the most part. I tried spraying water to help, but it only caused the binding of the bit. It does say dry, so stick with dry.

This could have been a packing mistake, but the pilot drill bit I received will not attach to the core bit.I haven't used it yet, but I'll need to buy another bit when it's time.

Review for 4.5" - This worked well to drill a 4.5" hole in brick for 4" RV bath fan. I first tried my Makita variable speed polisher which did not have enough power. I then finished the cut with my Dewalt 7" grinder which was burning up... Next time i would try to use a hole hawg and a plywood guide. I did purchase the centering bit as well but even with it, it was not quite right. My best suggestion for next time would be a plywood hole guide with the self centering bit that goes to a 1/2" chuck and use a hole hawg or something powerful that has a variable speed to get the low RPM. THe website has a suggested RPM depending on the hole size. After all that, an SDS bit and a chisel doesnt seem like a terrible way to do it after all.

good product

The center mason bit is too short. It doesn't allow it to be used as a guide so the Bit bounces until you can get it set. Even after I "predrilled" it, the Center piece mason bit was of little help so I replaced it with a longer bit. Drill slow and with water.

Great product

I usually don't write reviews. Do these bits work? Yes, but I they are not meant to be used constantly. Maybe used to get you by without the need to buy a larger heavier hammer drill. Our bosch bulldog hammer drill has more than enough torque. I have recently bought two 1 1/4 inch of these bits to use with the drill. Drilled 10 holes into cinder block walls than the metal cutting tip broke off. I bought a second one and the same thing happened after another 10 or so holes. They get the job done, but it stinks that the cutting tip keeps falling off these things.

Does the job, but the pilot bit is a little loose. I have to use a plywood as guide. Order a good quality bit adapter (not included).