Carbide Tipped Hole Cutters are designed for cutting steel plate, stainless steel, galvanized iron, fiberglass, aluminum, and copper up to 3/16” thick. Built-in safety stopper prevents over penetration. Ejector spring ejects slug to save production time. The center drill is a Titanium Nitride coated 135° split point drill. Used by electricians, plumbers, auto and truck repairmen, and general contractors. Outlasts hole saws 5 to 1.