SRAM XX1 Eagle AXS Upgrade Kit - Rear Derailleur for 52t Max Battery Eagle AXS Rocker Paddle Controller with Clamp Charger/Cord Black. The SRAM XX1 Eagle AXS Upgrade kit includes all of the electronic shifting components needed to introduce customizable AXS technology to your Eagle drivetrain. Includes the SRAM XX1 Eagle AXS rear derailleur with battery Eagle controller with clamp and charger and cord. The XX1 Eagle rear derailleur provides instantaneous shifting from a single touch even under the heaviest of loads and features a shorter cage that allows for 10mm more ground clearance and more chain wrap on the cassette. The Eagle AXS controller offers a unique wireless shifting experience with ergonomic touchpoints that are customizable to your preferences - you can choose what each button does through the AXS App