The LENOX Tools Bi-Metal Speed Slot Hole Saw with T3, 13/16"-21mm, has enhanced tooth geometry that cuts 50% faster than previous LENOX hole saw. Twice as durable as our previous generation when cutting through metal, this bi-metal hole saws features thicker walls to minimize tooth loss and improve durability. A staircase SPEED SLOT has a wide slot placed low on the hole saw and multiple leverage points to make it easy to work plugs out with a screwdriver. This design effectively removes sawdust and chips and helps prevent plugs from becoming stuck in the saw. 10% taller than previous models, it delivers cleaner cuts through two-by lumber.