Milwaukee 48-25-2121 2-1/8-Inch Bit with 7/16-Inch Shank Selfeed Bit
Has removable and replaceable feed screws. Two feed screws furnished with each bit.  Feed screw provides fast, effortless feeding even in gummy woods. Inside cutting plane shaves hole radius for clean, smooth holes without pressure. Bits has a 7/16 hex shank."