Our timing belt is composed of closed round rubber, with teeth and attached belt or pulley. When working, teeth and trough are in harmony and one movement will cause transmission of teeth, chain, and belt. it includs auto timing belt and industrial timing belt. Tooth shapes of Auto timing belt are mainly ZA, ZB, MR, RHD, RU, ZLB, STPD, RS, RPP, ZAS, Y, S8M and ZBS etc. Industrial timing belt using material as same as Automotive Timing belt, tooth shapes of this belt are mainly 3M, 8M, 5M, 14M. XXL. XL. L. XH. S8M and H etc.