Master Mechanic, 1 Piece 3-1/8" Bi-Metal Hole Saw, M3 High Speed Steel Cut 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, Clamshell Package.