The automotive industry uses fiberglass yarn in mufflers and for producing reinforcing cords for rubber belts and sheets in such applications as synchronous timing belts. High performance fibers offer strength, impact resistance, stiffness, temperature resistance, and fatigue resistance. Fiberglass yarn means longer life and narrower belts, saving space in engine compartments. Additionally, the use of fiberglass provides consistent performance and tension over a wide temperature range, reducing dependence on complex and expensive auto-tensioning devices.