Product details:

Drill America DEWCHAT Series 6 flute chatterless countersink is designed to provide more metal removal then the 1,2,3, and 4 flute countersinks. They are also more effective on harder materials. 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 tool holding 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".