Lightweight Upper Pulley for SRAM XX1, X01 and X1 Rear Derailleur. The complete pulley weighs about 40% less than the original one. Both washers are included. The outside of the pulley is the side where XY1 is written. The washer for the inner side of the Pulley is marked with an “i” for a simple assembly. Use ball bearings of the size 61800 or 6800. The recommended bearing is a rubber sealed deep groove ball bearing such as the 61800 2RS, 6800 2RS, 61800 2RSR or similar ones. Simply press the bearing into the pulley until it reaches its end position and sits tight.
This is only the upper pulley, for a set of two you also need to order the corresponding upper pulley: