These are all of our 15 mm wide 5 mm pitch HTD synchronous timing belt offerings. All of these belts are a composite of flexible rubber with a fiberglass tensile member throughout. Synchronous timing belts, also know as a toothed belt or synchronous belt, are designed to eliminate slippage and keep any number of objects rotating at a constant rate. We offer both genuine Gates brand belts as well as lower cost generic brand belts.