Made from high quality Chloropene Rubber (CR). CR material is treated for high ozone and weather resistance, low flammability, and high oil, fuel and chemical tolerance, offering greater resistance to contaminants and increased longevity. Dust Boots are an integral part of the ball joint or tie rod end - as soon as a boot is torn or damaged the likelihood of contaminants entering into the operating mechanism of the joint is extremely high. As soon as dirt & grit enter the component, excessive wear will follow. Avoid a costly repair bill, keep an eye on your dust boots, and if damaged replace immediately.