SRAM REAR RED ETAP XPLR AXS E1 13s SL46T MAX UDH BATTERY NOT INCLUDEDPart of Sram`s newest 13 speed gravel drivetrain, the eTap XPLR AXS E1 is packed with features to take your ride to the next level Hangerless Interface and Full Mount attachment allow for the most precise shifting and the ultimate resistance to impact 1x specific for use with 10 46T XPLR 13 speed cassette and Flattop chains Magic Wheel keeps the chain moving, even if debris enters the lower pulley Superior chain management with MTB inspired spring