Ice Hardened cryogenically treated for up to 50% longer life. Optimized tooth form for up to 2X faster cutting. Wide, angled and offset slots for easy plug access. Bi-metal construction with 8% cobalt for increased wear resistance. Quick Release Arbor Milwaukee Ice Hardened products utilize a proprietary cryogenic hardening process that improves upon traditional heat treat processes. Unlike surface coatings that wear away, cryogenics harden to the core by minimizing soft metal (austenite) and creating more hard metal (martensite). The result is a product that is more consistently hard throughout, resulting in life up to 50% longer than the competition. Kit Includes: Nine (9) Hole Saws: 3/4", 7/8", 1-1/8", 1-3/8", 1-1/2", 1-3/4", 2", 2-1/8", 2-1/2"; Two (2) Arbors: 49-56-7010, 49-56-7250; Two (2) Pilot Bits: 49-56-8010 (assembled with arbors).