... endless type 2.Strengthen cord is stainless steel A)Specification: XL, L, H, XH, T5, T10, T20, AT5, AT10, AT20, 3M ... bend performance and the good characteristics of the load force.XL OPEN TYPE TIMING BELT WIDTH(inch)Maximum Traction Force -OPEN ... Tolerance (mm)±0.3 Polyurethane Timing Belt,PU Timing Belt(XL)