Kit contains two belts for the HM122 & 722 portable sawmill. Set includes the BX series drive belt which runs from the clutch on the engine to the bandwheel and the opposing urethane belt on the other bandwheel. Belts should be replaced when the existing belts are within 1/16″ (1.6mm) from the top surface of the belt to the bandwheel. Part Number: HM122-1001