The shank fits the same-size chuck as standard drill bits, so you can spend less time setting up. Because these bits make very small holes, they’re often used for drilling circuit boards. Carbide bits are the the hardest and most wear resistant. They stay sharp at high temperatures and faster speeds for the best performance on hard and difficult-to-machine materials. Carbide can be brittle, however, so bits require a rigid machine tool holder to prevent breakage and should not be used in hand drilling applications.