When drilling holes through masonry walls (brick, block, stucco) dry core bits offer a tremendous advantage over carbide bits. It has been my experience over the years on numerous jobs sites to witness contractors employing a variety of tactics when penetrating masonry walls. Whether an electrician needs a two inch opening or an HVAC contractor needs a four inch vent, or even a plumber needs to run a six inch pipe, or maybe the fire sprinkler contractor needs to run through block fire wall; they usually grab their hammer drill and start drilling a Series of holes followed by some maul and chisel work. This type of drilling makesquite a mess and leaves behind a hole a bit larger than the one intended due to the “blow-out” produced by the hammering action of the carbide bit. When I see this I hop on their scaffold after receiving permission. In my hand is a dry core drill machine with the core bit required to drill the hole needed. One of the first things I have to verify is the hole size. Most contractors are so used to a hole that winds up much bigger than prescribed, I also need to point out that a diamond bit at two inches for instance will have a hole in the wall of precisely two inches. For this reason, the contractor needs to measure the o.d (outside diameter) of his pipe or duct and account for any escutcheon or flange or grill to be attached. My hand held drill has a variable speed trigger which helps to start the bit without walking on the wall. Provided there is no steel in the wall, these contractors are amazed at the speed at which an average brick and block wall can be drilled. There is generally very little clean up as the “cored” masonry remains inside the bit. Insulation and or fire caulking costs are greatly reduced as the hole is only slightly larger than the pipe. You wouldn’t believe how many of those contractors now ask me to drill such holes when I am on the job site doing my other drilling and cutting jobs. Try this on your next job and I am sure you will be satisfied.