They are made with a high temperature chloroprene polymer throughout the belt, and are proven through thousands of hours of customer use to be durable and dependable. DURA-SYNC TORQUE synchronous belts feature an HTD tooth profile.Timing Belt, 5M, 15 x 290mm PL, T58 They are manufactured to perform at identical or higher levels than all major US Manufacturerâs belts of the same type.