.80mm 4 Flute Ball Nose High Hardness Carbide End Mill, 4mm LOC, 3mm Shank, 38mm OAL, AlTiN Coated w/SE1 Edge Prep 4mm LOC,3mm Shank,38mm OAL GR Series: AT coated with SmoothEdge Prep, Thick core, high strength, high hardness solid carbide end mills with increased helix. Designed for milling of die & hardened steels & other hard metals. Tight diameter tolerance. Proprietary cemented carbide grade offers extremely high hardness and density. Strengthened cutting edges & reduced break-in with SmoothEdge SE1 for diameters less than 1/8\