Check the listing for details. KEO 50388 Countersink,82 deg.,3/8" Body 3P399. Condition: New. Listed at 20.45 USD. Countersink, 82 Degrees , 3/8 in, High Speed Steel, Bright (Uncoated) High-speed steel countersinks provide good wear resistance in a wide range of countersinking applications. General purpose 3-flute countersinks are the most commonly used type of countersink. They expand the top of an existing hole in a range of materials to ensure screws install flush with the surface of the workpiece. Three-flute countersinks typically provide better chip clearance and perform better when machining stringy materials than countersinks with more flutes.Countersinks expand the top of an existing hole in a workpiece to ensure screws install flush with the surface of the workpiece. This helps prevent the workpiece material from swelling when a screw is installed in the hole and tightened down in metalworkin.