Short Cage Rear Deraileur (10 speed)
This RD-6770 rear derailleur is a 10 speed RD and as such it isn't really used anymore. All current and previous Di2 generations have moved on to 11 speed.
Its low sprocket max is 28T and the top sprocket min is 11T. The max supported front difference is 16T and its total capacity is 33T.
Details & Specifications
E-Tube Port type:
Ultegra 6770 (Road)