Master Mechanic, 1 Piece 4″ Bi-Metal Hole Saw,M3 High Speed Steel Cutting Edge, 1-7/8″ Depth Of Cut, 4/6 Variable Tooth Pattern Provides Less Vibration, Delivering Faster, Smoother Cuts Then Conventional Hole Saws, Features Built In 3/8″ Mandrel Which May Be Used With 3/8″ Or Larger Drill, Recommended For Cutting Soft Or Hard Wood, Nail Embedded Wood, Stainless Steel, Pipe, Rubber & Conduit, ,Pilot Drill Included.