DIN335C, HSS, with cylindrical shank and 3 flutes.
Countersinks are deep-ground in the CBN Flutes. The 90° cone corresponds with the shape of the counter-sink screw or bolt head. Also available in 60°, 75°, and 120° versions. Radial back-off clearance makes it possible to work withour irattlingi, and also removes chipos and swarf perfectly.