A new level of performance for Shimano 12-speed road rear derailleurs. Wide 36T-compatible 12-speed Di2 rear derailleur. Receiving the wireless shifting signal from the shift lever, the Shimano Di2 105 rear derailleur completes a shift in the blink of an eye with its high-performance motor and optimized link structure. * A low-profile design reduces damage from contact and falls* Compact design includes an integrated wireless unit, charger, switch* LED status indicator* Wider range capacity