General description 4pcs HSS Counterbore End Mill set is designed for use with milling machines and high-speed carving machines. These milling cutters are capable of cutting various materials including copper, aluminum, tool steel, and cast iron. They offer high toughness and abrasion resistance, making them suitable for high-speed cutting of hard materials. The design allows for direct or fine processing in heat treatment molds, reducing the number of tool changes and improving machine actuator movement rates, ultimately saving time in mold making. Technical specifications M3: Blade diameter: 5.9 mm, Start: 3.2 mm, Shank diameter: 6 mm, Total length: 45 mm M4: Blade diameter: 7.4 mm, Start: 4.2 mm, Shank diameter: 6 mm, Total length: 48 mm M5: Blade diameter: 9.5 mm, Start: 5.2 mm, Shank diameter: 6 mm, Total length: 51 mm M6: Blade diameter: 11.0 mm, Start: 6.2 mm, Shank diameter: 8 mm, Total length: 58 mm M8: Blade diameter: 14.0 mm, Start: 8.2 mm, Handle diameter: 12 mm, Total