SRAM Force AXS eTap Rear Derailleur E1 

The SRAM Force AXS eTap Rear Derailleur E1 is lighter, faster and more capable than ever, and the Force AXS 12-Speed rear derailleur does it all in style. Covering cassette ranges from 10-28t up to 10-36t, this wireless wonder has a new, lighter cage and a larger pulley wheel to increase drivetrain efficiency. One derailleur ready for 2x or 1x, the steepest climbs and descents, all while shedding 12g from previous generation Force.