The Box One™ Rear Derailleur is the centerpiece in our first generation mountain bike drivetrain. Patent pending CamClutch™ technology reduces chain movement* and maintains chain tension. Housed in a carbon fiber/nylon composite body, the clutch mechanism uses a clever, one-way friction plate to increase tension as the cage moves forward and release tension as it travels back. Patent pending Pivot Tech™ works to prevent damage** in the event of crashes or trail-side impacts through the use of a spring loaded cable stop. With a maximum tooth count of 46, the Box One™ Rear Derailleur can easily handle today’s gear ratios and wide range cassettes. The inner and outer cages are made of durable cold forged aluminum and feature jockey wheels with sealed precision pulley bearings to reduce friction and avoid contamination.