Mill Diameter Inch 916 Number of Flutes 4 Material Cobalt Length of Cut Inch 138 Shank Diameter Inch 12 FinishCoating Bright Single or Double End Single Center Cutting Yes Overall Length Inch 338 Flute Direction Right Cutting Direction Right Variable Helix No Helix Angle 30 Centre cutting allows these end mills to drill into the part for the beginning of a slot These centre cutting end mills are recommended for pocketing, tracer milling, cam milling, die sinking and slotting