The SRAM eTap WiFli rear derailleur allows for acceptance of a wiser cassette ration. In short, this means you can run an 11-32t cassette to improve you climbing game. Pair this derailleur with the larger cassette and you can turn grinding into smooth pedal action. The rear derailleur is slightly lengthened to accept the larger gears, but not impede performance. We would consider this more of a mid-cage length derailleur, not the long cage variety of yesteryear.