Feature: 1. Round type frictiondrill (standard type frictiondrill) : frictiondrill penetrate the workpiece while drawing the bushing to form a convex ring. The surface of the boss, suitable for thread sealing or nut washer. 2. Flat type frictiondrill (designated flat frictiondrill) : the middle part of the drill grinding step melt cutter blades, and the hot melt drilling to penetrate the workpiece drawing to form a convex surface of the workpiece (ring cut milling and chamfer), make the surface smooth. 3. Material : tungsten steel 4. Use scene : metal processing 5. Wide range of applications, energy efficient Description: Category: drill bit Dimensions: M3 (2.7mm) / M4 (3.7mm) / M5 (4.5mm) / M6 (5.3mm) / M8 (7.3mm) / M10 (9.2mm) / M12 (10.9mm) / M14 (13mm) includes:1 x drill bit