This gear change rollers the Danish company CeramicSpeed consist of an extremely resistant and light titanium glass alloy (Liquid Metal) and represent the absolute high-end solution for all racers, place the highest value on minimum friction with the best power transmission. Derailleur rolls and especially their bearing must compensate for much friction. These rotate depending Translation 4-5 times faster than the crank and thus benefit particularly from a low-friction and durable bearing. Through its superior smooth running they eliminate pulling the chain on the gear change rollers. The special tooth profile improve the guidance of the chain and prevent the disengagement of track links. CeramicSpeed used in making the best materials and latest technologies to always to realize the highest possible quality. All products are handmade in Denmark. When installing any hydraulic presses are used. The manual assembly manufacturing tolerances are eliminated and always wholly owned fit guaranteed. To be really verbaust only the best of your bike.