Reducing friction was the main focus in the development of this product. The ball bearings are therefore made of Si3N4 grade ceramics, known for its low friction, and lubricated with grease to reduce maintenance requirements.
LOW FRICTION SEAL
This seal completely closes the ball bearings off from the outside world with as little friction as possible. As a result, there is no ingress of dirt and they run very smoothly, making them very durable and low maintenance.
Teflon is a smoother material than plastic, and adding it to the jockey wheel reduces the friction between the wheel and the bike chain.