Lenox, 2-1/4", 57mm, Bi Metal, Hole Saw, Vari Tooth Design, Positive Rake Tooth, Shock Resistant Teeth For Both Wood & Metal Cutting, Deep Aggressive Cutting Action, Speed Slot Design Makes Removing The Plug Faster & Easier, Use 2L, 3L, 6L, 7L Standard Arbor Or 2L, 6L Snap Back Arbor.