HSS Bi-Metal Hole Saws 1. M3M42 High Speed Bi-metal Edge Welded to Alloy Steel Back for Heavy Duty Cutting; 2. 46 variable Tooth; 3. Cutting Safely and Efficiently, the Best Way to Cut Large Holes, Clearing the Chips in tough Materials; 4. Cutting Depth to 1-12"(38mm) and 1-78"(4more...