Lenox Hole Saw (sizes 16L-20L) Features: *Bi-Metal *New, patented hole saw design keeps Lenox ahead of the competition *Shatter Resistant *Patented variable tooth set and height ensure that each tooth works independently, with super efficiency *Lenox's unique tooth shape evenly distributes cutting force over a wider area of the tooth *Virtually indestructible, they will cut faster and cleaner and last longer than other hole saws