5pcs HRC60 4Flute End Mills 1mm 1.5mm 2mm 2.5mm 3mm 4mm Carbide Flat End Mill Tungsten Spiral CNC Milling Cutter Router Bit Tool 12mm d12 30 d12 75 4 flutes hrc60 flat square end mills milling cutters cnc spiral router bits carbide cutter cnc tools