SRAM REAR RIVAL ETAP AXS D1 12s MED BLACK 36T MAX BATTERY NOT INCLUDEDThe precision and reliability of 12 speed eTap AXS, now at a whole new level Secure chain management and fast, precise shifting make for a smooth and quiet ride, every time Wireless electronic eTap shift logic for intuitive shifting, easy setup and reliability Compatible with both 1x and 2x drivetrains 36t cog max derailleur works with 10 28, 10 30, 10 33, and 10 36 cassettes X SYNC pulleys for increased durability and efficiency