These drill bits come in standard letter sizes. The trade letter size for each drill bit indicates its compatibility with other tools that have the same trade letter size. They have a TiN coating that protects them from wear and heat when drilling steel, stainless steel, and aluminum. These bits have spiral flutes that evacuate chips as the bits drill into a workpiece, and they have a straight shank that installs into a drill chuck or similar toolholder.,Non-coolant-through high-speed steel jobber-length drill bits do not have coolant holes, so a separate hose is required to bring coolant to the bits tip if it is needed. High-speed steel drill bits provide more flexibility and absorb more shock and vibration than cobalt, powdered-metal, and carbide drill bits, making them suitable for use in manual drilling machines and handheld power tools. They may leave a rough finish on the hole. Jobber-length drill bits are the most commonly used drill-bit length. They provide a good balance of strength and accuracy when drilling into a range of materials.