Milwaukee's core bits are ideal for large hole drilling where depth is relatively shallow. The core bit cuts a Kerf only. The usable depth of thick wall core bits is 4-3/8 In. The inside core must be removed by the operator before deeper drilling can be accomplished. The thick wall construction is ideal for larger hammers and more seasoned/cured concrete. A 7-1/2 In. extension is available to allow for the deeper holes to be drilled. The appropriate spline drive shank must be used to drive the core bit. Use 48-20-5199 center pin and 48-20-5174 guide plate for positioning and starting the hole. Thick wall core bits are available from 1 In. to 6 In. diameters.