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 USA. These 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.