Hello, my name is Peter Jennings, manufacturing & Supplier of mechanical products. Round urethane drive belt, (also called round belting, O-ring belts, or endless drive belts) for power transmission applications and live roller conveyors, i.e., line shaft conveyors and powered roller conveyors. Urethane round belts are elastomeric belts, meaning they are designed to stretch, so they do not require a belt tensioner. If you also want to purchase the belts you may visit the online store.