The OSPW X System reduces friction 35-40% over stock pulley configuration. The lightweight custom molded carbon fiber cage ensures durability. This design allows the use of the same length chain as stock pulleys. The 14-tooth upper and 18-tooth lower pulley profiles ensure stable chain retention without added drag. The OSPW X System is developed, designed and handbuilt in Denmark - and test proven globally. Only compatible with 1X specific derailleurs. In the box:-Complete OSPW System for Shimano XT/XTR 1x12-CeramicSpeed Pulley Oil, 15 ml. -Sticker Sheet