So long as your Shimano 9-10 speed rear derailleurs are still performing, improve their performance with pulleys that both reduce friction and increase lifespan. Ours are designed to work with less drag, adding to the power transmitted to the rear wheel. We have two options for Shimano 9-10 Speed derailleurs. The first is machined aluminium pulleys that start with our hardened-steel races and are finished with our CeramicSpeed Balls—our Standard Bearings. These kill the competition in tests. Option two is machined titanium pulleys with our Standard Bearings. The third is machined titanium pulleys with our stock ceramic balls installed in our coated hardened-steel races.Compatible with all 9-10 speed Shimano derailleurs. In the box: 2 11-tooth pulley wheels 4 spacers CeramicSpeed Oil for Pulley Wheel Bearings, 15ml dropper bottle Decal