XIANQI [HSS Counterbore End Mill]: These end mill cutters are made of hard high speed steel, High toughness, abrasion resistance, high-speed cutting for the high hardness [Application]: Our M3-M8 professional counter bore bits are usually used to be assembled on milling machine; Suitable for milling of copper, aluminum, steel, cast iron, etc [Well Performance]: This counterbore set can processing directly or fine processing to the heat treatment mold [High Effective]: Reduces times of changing tools, improves machine actuator movement efficiency and save mold making time [5pcs/Set M3 M4 M5 M6 M8]: 5pcs M3-M8 countersink end mill cutters drill bits set 4 flute metal drilling slot drill bit woodworking pilot milling cutting tools set Specifications: color: as show 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*12*67mm Weight: 128g(approx.) Package Includes: 5 x Countersink Mill Cutters