Fits models 421 and 521 snowthrowers. Kevlar® corded lawn and garden belts have become increasingly popular over the last few years due to their extreme strength, durability, and value-added pricing. Kevlar® corded belts, also called Aramid or extra-heavy duty belts are constructed of organic polyaramide fibers that are manufactured using complex chemical processes. **Interesting fact: Kevlar® is the same material bulletproof vests are constructed with. Kevlar® is used in PIX belts as a tension member because of its inherent stability and high tensile strength Cord.