Stub-length screw machine twist drills have a shorter overall length than jobbers' length bits for maximum rigidity and longer tool life. Also known as stub drills, they're designed primarily for machining operations in screw machines but can also be used in manual hand held drills. High Speed Steel models are best suited for drilling steel, cast steel, cast iron, or other alloyed or non-alloyed ferrous materials, but they also work well for a variety of non-ferrous and non-metallic materials. Coated solid carbide designs can result in three to five times the penetration of HSS drills, often eliminating the need for reaming and spot drilling. For optimal performance and the best tool life, suitable lubricating/cutting oils or the appropriate coolant fluids are recommended.