Hole Saw, 3-5/8", Bi-Metal Construction, for Wood, Aluminum, Copper and Stainless Steel, Boxed Variable pitch bi-metal hole saws with super sharp teeth cut faster and dulls less. Best suited for maintenance and repair work. Variable depth gullets provide more efficient chip clearance. 4/6 Variable pitch teeth for reduced noise and improved performance. Electron beam weld for stronger, longer lasting teeth. Bi-metal construction for toughness and long life.