Features and Benefits: 3) 3/8 ” Cutters; fit 3/8″ and 1/2″ hand held drill chucks Arbor Assembly (11123) with skip proof Pilot Extra pilot included Made of M2 High Speed Steel Made in the USAThese annular tools cut clean burr-free and round holes fast unlike twist drills that push or hole saws that tear through materials. There s no dead zone so less thrust is required and no deforming of stock or jagged edges occurs. The cutters are for the heavy-duty use in sheet metal and materials up to 1/2″ thick. Multiple cutting teeth precision ground which allows for a long tool life. These cutters are packaged in a plastic carrying case.