Use SD-3 Counterbores to drill a pilot hole and counterbore a flat bottomed hole in one step. Perfect for lag screws, lag bolts, washer head screws, T-nuts & more.
Drive Shank: 1/4" Hex Power Bit Shank
Drill Size: 7/16"
Counterbore Size: 1"
7/16" x 1" 3-Flute Flat Bottom Counterbore with TiN coated twist drill