Description: Countersink end mill cutter is a special made tool mainly used to cut such a hole allows the head of a bolt or screw. This kind of cutter cut hole and bottom hole with high alignment precision, Due to its high production efficiency, it is commonly used for machining industry. Features: Mill cutters are made of hard high speed steel, usually used to be assembled on milling machine.Suitable for milling of copper, aluminum, steel, cast iron, etc. High toughness, abrasion resistance, high-speed cutting for the high hardness. Can processing directly or fine processing to the heat treatment mold. Reduces times of changing tools, improves machine actuator movement efficiency and save mold making time. Specifications: Material: HSS-AL super-hard high speed steel Hardness: HRC65~68° Size:(Boot*Blade Diameter*Shank Diameter*Full Length) M3=3.2*5.9*6*45mm M4=4.2*7.4*6*48mm M5=5.2*8.9*6*51mm M6=6.2*10.4*8*58mm M8=8.2*13.4*10*67mm Weight: 128g(approx.) Package Includes: 1 Set(5pcs) x Countersink Mill Cutters Note:1. Please allow 1-2mm error due to manual measurement. Thanks for your understanding.2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard. .