5mm 4 Flute Square End High Hardness Carbide End Mill, 20mm LOC, 5mm Shank, 50mm OAL, AlTiN Coated w/SE4 Edge Prep 20mm LOC,5mm Shank,50mm 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\