Avoid clogs and dissipate heat with cobalt bits that last at least twice as long as high-speed steel. The flutes clear chips to improve coolant flow and prevent damage to the bit and the hole. They also speed up drilling since you don't have to stop to clear the bit manually.

The flutes spiral in the opposite direction of other bits and stay sharp longer than high-speed steel. They’re primarily used to remove stripped screws. Choose a bit that’s slightly smaller than the diameter of the screw’s head. Set your power tool to rotate in reverse. Slowly drill in the center of the screw head, maintaining constant pressure. As the bit penetrates, it will catch onto the screw and reverse it out of the hole. If the screw is badly stripped, you might need to punch a starter hole. Also known as reverse-flute bits.

When one end wears out, switch to the opposite end for two times the life of a standard cobalt steel end mill. With better heat and wear resistance than high-speed steel, these cobalt steel end mills can run at higher speeds and provide better performance on hard material, such as iron, hardened steel, titanium, and tool steel. Their square ends make them good for milling square slots, pockets, and edges. All are center cutting, allowing plunge cuts into a surface.

When one end wears out, switch to the opposite end for two times the life of a standard high-speed steel end mill. Made of high-speed steel, these end mills are for general purpose milling in most material, such as aluminum, brass, bronze, iron, and steel. Their square ends make them good for milling square slots, pockets, and edges. All are center cutting, allowing plunge cuts into a surface.

End mills with fewer flutes provide better chip clearance for high-volume, high-speed plunge, slotting, and roughing cuts; end mills with more flutes provide a finer finish and operate with less vibration when run at high speeds.