Reducing friction was the main focus in the development of this product. Teflon is a smoother material than plastic, and adding it to the jockey wheel reduces the friction between the wheel and the bike chain. The ball bearings are made of Si3N4 grade ceramics, known for their low friction, and lubricated with grease to reduce maintenance requirements. In addition, a low friction seal is used. Suitable for road and mountain bikes (SRAM).