The Record 12-Speed rear derailleur has an innovative shape that envelopes the cassette better, thanks to 3D Embrace technology, creating a double effect: allowing the chain to maintain optimum traction at all times, thus increasing the speed, power and precision of shifting. Optimized to work with cassettes from 11 to 34 teeth. Carbon fiber-reinforced construction, to increase strength while keeping weight to a minimum. 12-tooth pulley wheels for smoother chain movement. Campy 12-Speed Chorus/Record/Super Record 2019+. REAR DERAILLEUR MOUNT TYPE. CHAIN WRAP CAPACITY (TEETH).