Design: Very good chip removal and ideal chip flow due to spiral grooves. Easily resharpenable. The countersink is secured against twisting in the holder. Note: Flanged countersinks are also available in HSS with optional TiN coating, as well as with soldered carbide cutting edges and with ISO indexable inserts type "T" upon request. Use: For countersinking screws according to DIN or, through the appropriate combination of countersink and pin, for creating stepped holes or countersinks outside of the standard.