SRAM DualDrive Clickbox

SRAM's DualDrive is a unique drivetrain that combines a three-speed internal-gear hub with an external cassette and derailleur. The result is a wide-range of gears in a clean, one handed control system. SRAM's DualDrive Clickbox attaches to the DualDrive hub—and the DualDrive shifter via cable—so you can shift between the hub's three internal gears.