15 Piece General Purpose Ice Hardened Hole Saw Kit 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 (marten site). The result is a product that is more consistently hard throughout, resulting in life up to 50% longer than the competition. Features: Package of 15 Ice Hardened to Last Longer Bi-Metal Construction Includes Eleven Hole Saws, Two Arbors, Two Additional Bits, One Adapter, and One Spacer Since its founding in 1924, Milwaukee has focused on a single vision: To produce the best heavy-duty electric power tools and accessories available to the professional user. Today, the Milwaukee name stands for the highest quality, durable and reliable professional tools money can buy.