IRWIN Marples Wood Drilling Forstner bits are constructed of tough carbon steel to stay sharp and produce precise pocket holes and flat-bottomed (blind) holes. The ultra-sharp knife edge design cuts more quickly and accurately through hard and soft woods than traditional forstner bits. With a reduced shank, these bits fit 3/8" and larger drills and drill presses, these wood drill bits are ideal for fine woodworking, cabinet-making and more.