This is my v.3 of the Denver Obs. chair. Seat height starts from 50cm up to 120cm, about right for my 16"f5 Telekit Dob. The footrest is used for the primary height adjustment with final adjustment via the (25cm travel) actuator, which has a small wireless handset. This is a great setup for extended obs. of a particular area, not so much for the Messier Marathon type sessions, though it is far better than my original 'all manual' chair. There's nothing better than being able to get your seat height spot on easily - no more straining for that ideal EP focus.
The chair folds flat easily after removing 2 screws which locate the actuator & weighs around 10kg.
Ian.