This is an updated version of the Oversized Pulley Wheel System for Shimano 9100/9150 and 8000 SS/8050 SS . This new design has an integrated stop tower for easier mounting. The CeramicSpeed Oversized Pulley Wheels System has been proven to be the fastest pulley system in the world, providing energy savings starting from 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 cycling teams and professional triathletes. Featuring a 13-tooth upper pulley wheel and a 19-tooth lower pulley wheel to provide absolute optimisation of the rear derailleur. The upper and lower oversized aluminium pulley wheels come fitted with either standard or coated CeramicSpeed Bearings. Please note: The OSPW System for 9100/9150 and 8000 SS/8050 SS is not compatible with Ultegra 8000-GS or 8050-GS (medium cage) derailleurs, nor with the clutch equipped Ultegra RD RX800 & RX805. Please see our OSPW X for Shimano RX800/805 for a compatible RX800 & RX805 version. For a compatible upgrade for Ultegra 8000-GS or 8050-GS please see our Pulley Wheels for Shimano, 11s NW. While there is design similarities this OSPW is not compatible with the 12-speed Shimano 9200 or 8100 series derailleurs. The Shimano 9100/8000 OSPW system is compatible up to a 32 tooth cassette for both Dura Ace & Ultegra derailluers In the box: Complete OSPW for Shimano 9100/9150 and 8000 SS/8050 SS system CeramicSpeed Oil for Pulley Wheel Bearings, 15ml. dropper bottle