Here's an updated version of the Ceramicspeed oversize derailleur clevis for Shimano Dura Ace 9100/9150 and Ultegra 8000 SS/8050 SS derailleurs. This new design has an integrated stop tower for easier mounting. The CeramicSpeed system has proven to be the world's most rapide oversized derailleur clevis system, offering energy savings of as much as 2.4 watts over standard Shimano systems. The OSPW system for Shimano 9100/9150 and 8000 SS/8050 SS is an industry-leading product, chosen by many of the world's leading professional cycling and triathlon teams premier. It features a 13-tooth upper pulley and a 19-tooth lower pulley for absolute rear derailleur optimization. Oversized aluminum upper and lower pulleys feature standard or coated CeramicSpeed bearings. Details : Only compatible with Shimano Ultegra R8000/8050 - Dura Ace R9100/9150 groupsets Carbon clevis Lifetime durability 3 to 5 times greater than conventional bearings. Ceramic balls 58% lighter, 121% stronger and 68% harder than steel balls. Grade 3 ceramic balls (polished for over 45 days) for virtually no friction. Design and manufacture and assembly at France. Please follow the assembly instructions or visit your local dealer if in doubt. The Shimano 9100/8000 OSPW system is compatible up to a 32-tooth cassette for Dura Ace and Ultegra derailleurs. In the box: OSPW system complete with 13 teeth/19 teeth + CeramicSpeed oil for pulley bearings, 15 ml dropper bottle. Please note that, despite similarities in design, this OSPW is not compatible for use with Shimano 9200 or 8100 12-speed derailleurs.