Product details:

Drill America DEWMSK series 4 flute machine countersink is designed for countersinking holes for centers or for enlarge existing holes. High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance. Round shanks allow use with a wide variety of toolholding systems. Through-hole flute style has a single flute that passes through the cutting head to reduce vibration and chip clogging; also called "zero flute".