snippet: Size: 5/16, Material: High Speed Steel, Finish: Uncoated (Bright), Overall Length: 2, Shank Size: 1/4, Shank Type: Round, Number of Flutes: 6, Cutting Angle: 90 6 Flute chatterless countersinks are designed to provide more metal removes than the 1,2,3 and 4 flute countersinks. They are also more effective on harder materials. (Page 1)