The development of this product was focused on reducing friction. The bearings are therefore made of ceramic grade Si3N4, known for its low friction, and lubricated with grease so that almost no maintenance is required.
LOW FRICTION SEAL
This seal completely seals the bearings from the outside world, with as little friction as possible. This prevents dirt from getting in and they run very smoothly. They are therefore very easy to maintain and last a long time.
Teflon is a smoother material than plastic and by adding it to the wheel the friction between the wheel and the bicycle chain is reduced.