Sram xx1 eagle 21 12 speed rear derailleurthis new derailleur not only answers the eagle drivetrains need for greater capacity but is also the next evolution of srams proven 1x specific x horizon design the larger 14 tooth x sync lower pulley allows 10 to 50 tooth cassette capacity in this compact design and also adds to eagles overall smooth pedalling feel srams new type 3 roller bearing clutch features a smoother torque curve for a quieter more consistent operation and feel c