Material makes the difference: Exact Actuation™ combined with materials upgrades yields world-beating performance & weight savings Light weight&44; precision&44; & fluid performance put the new SRAM Red Rear Derailleur in a class of its own Based on the already-superior design of the SRAM Force Rear Derailleur&44; the Red offering delivers even greater advantages thanks to a diet of structural carbon & titanium Hybrid ceramic bearing pulleys & titanium parallelogram pivot bearing refinements further supercharge the overall component speed&44; accuracy&44; & durability Amazingly&44; these design choices yield an astonishing 153g mechanism Exact Actuation 10 Speed 153g Aluminum B-Knuckle&44; Carbon-Fiber Inner Black Box™ Ceramic Bearing Pulleys Max tooth 28T