4.5mm 2 Flute Ball Nose High Hardness Carbide End Mill, 20mm LOC, 5mm Shank, 50mm OAL, D1 - PVD Diamond Coated 20mm LOC,5mm Shank,50mm OAL GR Series: D1 PVD Diamond coated high strength, high hardness solid carbide end mills for graphite & abrasive materials featuring proprietary coating for medium to long-run setups. Designed for graphite and abrasive non-metals. Proprietary cemented carbide grade, application specific geometry and D1 PVD diamond coating. Hard, thin and smooth D1 for extremely sharp cutting edge. Superior abrasion resistance for superb price / performance valuation. Extremely close diameter tolerances. Round Tool Laboratories USA Part #10644