4mm 4 Flute w/1.0mm Radius High Hardness Carbide End Mill, 20mm LOC, 4mm Shank, 50mm OAL, D2 - CVD Diamond Coated 20mm LOC,4mm Shank,50mm OAL GR Series: D2 CVD Diamond coated high strength, high hardness solid carbide end mills for graphite & abrasive materials featuring proprietary CVD diamond coating for long-run setups. Designed for graphite and abrasive non-metals. Proprietary cemented carbide grade, application specific geometry and D2 CVD diamond coating. Our hardest, thickest, longest lasting diamond coating. Maximum tool life and wear resistance for long production runs. Tight diameter tolerances for CVD diamond. Round Tool Laboratories USA Part #00187