The 240L X .50" Timing Belt for 20" Machine comes with temperature stresses, static dissipating, and resistance to oil. The belts are developed to improve capacity with outstanding performance at higher speeds on a smaller diameter pulley system. The heavy-duty belt is made out of a specially formulated. rubber compound with direction oriented fibers that cut noise and provide very high flexibility and stability. It works for all 240L X .50" machines and for models purchased before April 2015.