The diamond-grit edge on these hole saws cuts more accurately, leaves a smoother finish, and lasts up to twice as long as carbide-grit-coated teeth. Saws are for use on reinforced plastic, Kevlar, stone, brick, and other abrasive materials with high silicon content. Attach them to a drill or drill press. An arbor with pilot drill (sold separately) is required. To cut ceramic tile, you must use a 1/4" carbide-tipped pilot drill.