The support rod has a special round head which is inserted into the hole of the plate and secured in place with a cotter pin from the back side of the plate.
The height adjustment is done with a quick finger screw. Open the screw, adjust the instrument to the desired height and lock it up again. Nice and quick. The horn is now floating at the desired height on a smooth spring.
Playing standing up
When you play standing up, you just put the bottom of the support tube into a specially made belt pocket. You just slip the belt through the holes on the plate.
Adjust the desired height and play. The trumpet is very easily turned to any direction so it will not be awkwardly stiff. Now the weight of the horn - and your left hand which is leaning on the horn! - is transmitted to your legs. This is very comfortable feeling.
Now you can walk and even march while playing!