Die springs are helical compression springs that are made from rectangular wire. For the same deflection, they can carry roughly 30% more load than compression springs that use round wire. Die springs are used mainly in die machines, but are suitable for a variety of high-static applications where maximum cycle-life is important. Applications include brakes, clutches, agricultural equipment, and aircraft components. Most die springs are made of oil-tempered and chrome-alloy metals. Because surface defects can significantly reduce a spring’s fatigue life, the spring wire may be specially-treated and cost more than commercial-grade materials. Chrome-silicon wire has a lower tensile strength than commercial-grade music wire, but features a higher maximum service temperature.