The absoluteBLACK HOLLOWcage Oversized Derailleur Pulley Cage is expertly designed for Shimano Dura-Ace 9250 and Ultegra 8150 12-speed derailleurs, delivering unparalleled performance and whisper-quiet operation. Constructed with a carbon-polymer mono-plate, this cage integrates bespoke oversized full ceramic bearings, ensuring exceptional durability and efficiency.Engineered specifically for Shimano Dura-Ace 9250 and Ultegra 8150 drivetrainsCompatible with cassettes up to 34tFeatures the Silent Xring Pulley, which effectively dampens chain impact on the guide pulley teeth, minimizing engagement noiseSignificantly reduces noise levels (over 5-7dB quieter compared to stock options)Utilizes full ceramic bearings made from Silicon Nitride ceramic balls and Zirconia Oxide ceramic races for enhanced stiffness and shifting precisionWeighs just 71g, making it one of the lightest oversized cages on the market