Optimised Wireless Drivetrain Performance Using SRAM's proprietary wireless communication protocol, utilising 128-bit encryption, the shifts are quick, clean & crisp. The system optimises Yaw adjustments as required throughout the shift range, there's no rider input needed, you just click & the derailleur smoothly & cleanly engages the front ring you want. Modern Shifting Elegance The AIREA Wireless system makes this system set up superbly simple & provides a clean & uncluttered finish to any bike. Mechanical necessities such as a carbon pulley cage, ceramic pulley bearings, & anodized alloy artfully blend with proprietary electronic advancements to deliver modern shifting elegance. Simple, Efficient & Hassle-Free The derailleur is powered by SRAM e Tap batteries that are easy to install & remove; they literally snap to remove & charge. Simply flip open the battery latch, which is tool-free in function & slide the battery up & out of the derailleur. You then simply snap the fully charged battery into place & mount depleted battery into the USB (Universal Serial Bus) powered charger, & connect the charger to any USB (Universal Serial Bus) power source or A/C USB (Universal Serial Bus) adaptor. A full charge takes just 45 minutes to complete.