They are manufactured to perform at identical or higher levels than other popular brands on the market like Winkler.The backing attaches the individual belts together, and is made of heavy duty woven fabric encapsulated in rubber for superior flexibility. The helically wound tensile cords are specially manufactured with, twisted, heat and chemically set, polyester material. The body rubber is a highly engineered synthetic rubber compound, specially compounded for cool running, crack resistance, and excellent bonding to the outside fabric and tensile cords.