The SRAM XX1 Eagle AXS Upgrade Kit offers the pinnacle of performance, paired with the connected components of Eagle AXS. This upgrade kit includes a derailleur, controller, cage, and charger. The kit features Eagle Technology, which represents the newest 1x drivetrain technology that is a lighter, simpler, more durable and easier to use drivetrain. Eagle features all new 1x components, engineered for even greater durability and performance while maintaining a significant weight advantage over other drivetrain solutions. Its AXS is a SRAM new bike component integration system that connects electronic bicycle components and software, allowing riders to see battery status, change component behavior, personalize controls, get maintenance reminders and update firmware. The relationship between bottom bracket spindle and bearing is the core of DUB technology, as it is where stiffness meets durability. SRAM took this concept it a step beyond conventional thinking and made everything simpler, providing a better integration of the relationship between chainring, crank, spindle and bottom bracket, developing a complete system that equals better drivetrain performance. Get ready for the new generation of super bikes with the SRAM XX1 Eagle AXS Upgrade Kit!