Shimano pulley wheels for XT 11v ( RD-M8000 )Set of rear derailleur pulleys valid for Shimano XT 11v (RD-M8000). Shimano pulley wheels for XT 11v ( RD-M8000 )Set of rear derailleur pulleys valid for Shimano XT 11v (RD-M8000).The sheaves or pulleys of the gearbox are responsible for transmitting the movement of the gearbox to the chain and regulating its tension, therefore, they are parts subject to wear and tear and are responsible for the proper functioning and smoothness of the gearbox.They are one of the most neglected parts in transmission maintenance and very easy to control and replace (you just have to pay attention to the marks that indicate the direction of rotation and which is the upper and which is the lower).It is important to make sure that they are compatible with our change.ref.: 5RT98120