Professional twist drills: set of 13 pieces: 1.5mm (1/16"), 2mm (5/64"), 2.5mm (3/32"), 3mm (7/64"), 3.2mm (1/8"), 3.5mm (9/16"). 162.6 cm cm), 4 mm (5/32"), 4.5 mm (11/64"), 4.8 mm (3/16"), 5 mm (13/64"), 5.5 mm ( 7/32"), 6 mm (15/64"), 6.5 mm (15/64"). /10.2 cm High quality material: The drill bits are made of made of high speed steel with titanium coating, which has super heat resistance and long service life. Quickly replace the drill bit: The 6. 35mm is suitable for all power tools, which is more easy/convenient/safe to use. It is suitable for electric screwdrivers, drill bits, etc., or for standard drill chucks. Smooth drilling: designed as a 135° cutting angle, which can automatically center and penetrate quickly with a small amount of pressure. Threaded flutes can remove chips and debris faster. After-sales service: All twist drill bits daux support worry-free after-sales service. We provide high-quality products and timely after-sales service.