The SunXCD rear derailleur is a long cage rear derailleur suitable for touring and road use. The long cage allows use of a wide-range cassette (11-34t max) and with a maximum capacity of 39t. Some good examples would be running something like -
The return spring is nice and strong, which is essential on a touring bike. There is a barrell adjuster for easy 'on-the-go' gear adjustments. Compatible with up to 10 speed (Shimano fit). Possibly the only long cage rear mech with a polished finish. 230g.
Note - I have used this mech with a 11-42t cassette with some success :)