BKCJ – 0340 – 11 tooth, XD15 Ceramic Hybrid Bearing, Machined Delrin Derailleur Pulleys for 11 speed Shimano Dura Ace (9000 Series) and Ultegra (8000 Series) Derailleurs (5mm bolt hole) The ultimate upgrade pulley. Guaranteed to last forever against corrosion Precision machined Delrin Derailleur pulleys featuring XD15 Ceramic – Hybrid, radial bearings for enhanced shifting performance and longevity. Designed and manufactured for performance, these pulleys feature CN (tight clearance) bearings in the upper pulley to maximize shifting accuracy and C4 (loose clearance) bearings in the lower pulley to allow for chain – line movement. 5 The eleven tooth size and profile with 5mm bolt – holes are designed as an upgrade for most 11 speed Shimano Dura Ace and Ultegra derailleurs. Enduro Derailleur Pulleys are available in a number of configurations and performance levels and are all are proudly precision manufactured in the USA.