... efficiency,bearing wear and oil, good performance, dynamic buckling resistance PU open belt specifications:1) S2m, S3m, S5m, S8m2) 2M, 3M ... , 5M, 8M3) MXL, XL, L, H, XH, XXL4) T2.5, (D)T5, (D)T10, (D ... )AT5, (D)AT10, T20PU timing belts/pu open beltsDetails:1) material: polyurethane, nylon, steel, or kevlar cord2 ...