Trend Professional Window Industry Cutters Three Flute 90 Degree Countersink Cutter 49/50X1/4HSS - 12.7mm Diameter Key Features: This countersink can be used at high speeds for countersinking alloy All aluminium tooling should be used with a coolant, wax stick or lubricant Material should be securely clamped Specification: D: 1/2 inch (imperial diameter) D: 12.7 mm (metric diameter) OL: 60 mm (overall length) Shank Diameter: 1/4 inch Recommended speed: 1000-10000 rpm