When I was on vacation last week I went to a local park and they had a pull-up station with 4 different height bars and a ring station with two sets of rings at different levels. :!:
I decided to try a muscle-up for the first time and realized I had a long way to go. I couldn't do one on the high rings, even when jumping. On the lower rings I was able to some with a jump assist.
The experiment led me to believe that I need to get or make a set of rings for training. The ring dips I were doing were very challenging and I could definitely feel the benefit of the rings.
But mostly I just thought it was cool that they had a ring station.