145615 Milwaukee Elec Tool 49-56-7010 3/8, Hole Saw Arbor, Small, Durable Hardened Steel Construction Alloy Steel For Greater Durability, Features A Hex Shank Which Can Be Used With Any 3/8 Extension, Fits All Hole Saws Up To 1-3/16, Fits All Drill Chucks 3/8 Larger.