Proline PTC4-7/8 Diamond Grit Multi-Purpose Hole Saw Cutter The industrial diamond grit is vacuum brazed to the raised cutting edge of the hole cutter Raised edge ensures accurate positioning The thin walls enable rapid penetration and reduce heat build up Core removal ejection slots allows for the easy removal of the material slug Use with PTC4 Hole Cutters: PTC4-ARBOR-1 for sizes  thru 1-1/8-inch hole saws