Main materials used in "V" and wedge belts: Polyester Polychloroprene Natural Rubber SB Rubber (Styrene-Butadiene) PB Rubber (Poly-Butadiene) Cotton Sulphur Carbon black Plus small quantities of other material Main materials used in timing belts: Classical HiTD Polyurethane metric (T2.5, T5, T10, AT2.5, AT5, AT10) Polyurethane metric (T2.5, T5, T10, AT2.5, AT5, AT10) (MXL, L, H, XH,XXH) (3M, 5M, 8M, 14M) Truly Endless Open Ended Tensile member (cord) Fiberglass Fiberglass Steel cord / Kevlar cord Steel cord / Kevlar cord Tooth compound CR CR Polyurethane Polyurethane Tooth facing fabric Nylon Nylon no fabric Nylon available Backing fabric CR CR no fabric Nylon available Belts could be stored for 7 (seven) years without affecting expected working life if the storage is done in optimum conditions.