Tool-free operation. Universal, quick change with all brands of hole saws. No adapters required. Durable hardened steel construction. No. 49-56-7250: Shank Diameter: 3/8" Hex, Hole Size: 1-1/4" and Larger, For Use With: Drill Chucks 3/8" and Larger, Pkg Qty: 1, Package Type: Card No. 49-56-7240: Shank Diameter: 7/16" Hex, Hole Size: 1-1/4" and Larger, For Use With: Drill Chucks 1/2" and Larger, Pkg Qty: 1, Package Type: Card No. 49-56-9100: Shank Diameter: 7/16" Hex, Hole Size: 1-1/4" and Larger, For Use With: Drill Chucks 1/2" and Larger, Pkg Qty: 1, Package Type: Card