A proprietary cryogenic hardening process hardens to the core and has up to a 50% longer life. Optimized tooth form for up to 2X faster cutting and wide, angled, and offset slots for easy plug access. For use with steel, non-ferrous metals, wood, plastic. Set includes (11) hole saws: 3/4", 7/8", 1", 1-1/8", 1-3/8", 1-1/2", 1-3/4", 2", 2-1/8", 2-1/4", 2-1/2", (2) arbors with pilot bits, (2) pilot bits, (1) adapter, and (1) spacer. Room for additional hole saw and arbor storage. No. 49-22-4175: Material: Bi-Metal, Pieces In Set: 15 Pcs., Pkg Qty: 1, Package Type: Box