Featuring a ceramic design, these replacement rear mech pulleys ensure light and smooth shifting operation as you conquer your way around the mountain. Specifically designed for use with SRAM XX1/X01 Eagle rear derailleurs. X-SYNC Technology Compatible SRAM X-SYNC 1x chainrings provide the highest level of performance and durability. The SRAM X-SYNC tall square teeth edges engage the chain earlier than traditional triangle-shaped teeth. The sharp and narrow tooth profile, as well as rounded chamfer edges, help manage a deflected chain. To provide the best possible performance in muddy conditions, the X-SYNC chainrings have been designed with mud-clearing recesses for the inner chain links and rollers. Engineered in Germany, X-SYNC rings are an integral part of the SRAM 1x drivetrain. Accept no imitation. Use only SRAM parts with SRAM components. Installation of parts and accessories not originally intended could result in less than optimal performance and/or injury. Rear Derailleur Compatibility RD-X0-1-B1, RD-X0-1-B2, RD-X0-1E-A1, RD-XX-1-B1, RD-XX-1-B2, RD-XX-1E-A1. Manufacturer's Part Number: 00.7518.103.000 Black Pair - XX1/X01