You will receive 30 pieces of cobalt drill bits, double-ended, drilling diameter 1/8 inch, enough quantity to meet your daily use needs; please pay attention to control the speed, pressure and heat when applying the drill bits Suitable size: Twist double drill bit set is about 1/8 inch in diameter and about 1.89 inches / 4.8 cm long, M35 carbide cobalt double drill bits are the right size and easy to match with other drills such as lithium drills, electric drills, hand drills, impact drills (excluding) etc. Reliable to use: The cobalt drill bit is mainly made of M35 contains cobalt, which is strong, heat-resistant, wear-resistant, reliable, and has a long service life; because the is hardened and ground, the drill bit has accurate cutting operation and no need to worry about shaking Double-ended twist design: Each drill bit has 2 cutting points. You can use the cobalt drill bit set to drill 2 holes at each end to improve drilling efficiency; the cobalt drill bit adopts a 135-degree