When you've already settled on the best of the best, there's no going back. If you've got Shimano's newest M9000 parts, you'll undoubtedly need Shimano's XTR M9000 Derailleur Pulley Set at some point. The pulleys are lightweight and designed to shed mud as quickly and completely as possible and should mud get in there (which it obviously will), sealed cartridge bearings will keep the grit on the outside. Stay at the top of the podium and don't ever settle for second place.   Features 11 speed compatible. 11 teeth per pulley. Sealed cartridge bearings. Mud-shedding design. Lightweight. Includes tension and guide pulleys. Shimano part # Y5PV98160.