||04-05-2013 02:46 PM
Found that in a good review (and it rings true with my memory)
"I purchased two bits: 1 3/4 inch and 2-5/8 inch for plumbing purposes. We use these core bits nearly every day. The trick is to drill a 3/8" pilot hole completely through your work first. Then change to the core bit and let it do its work. Drill 3/4 of the way throughfirst, then finish from the other side. A perfectly clean and smooth hole with little mess every time. This bit has more teeth than most others and is built with better steel and has a thicker boby than any other brand. It cuts through common brick, hardened face brick, concrete and prestressed (Flexicore) almost effortlessly. And they last a long, long time. Definatley worth every penny many times over."
as per joe sainz. bosch accesories rep, he comes from a background in commercial concrete work