Belt, Fan (GAS SN 501 > ). PART NO: A-351321R1. The Kevlar Blue V-Belt is an extra heavy duty belt constructed of organic polyamide fibers. The polyamide fibers are created by a complex chemical process. This process allows the Kevlar belts to have a high resistance to repeated reverse flexing, oil, heat and cracking. Kevlar belts also offer high tensile strength, non-extensibility, and high resistance to shock loads. . MODELS: Case-IH TRACTOR: CUB (GAS SN 501 > ).