Push the pink button and move glass slider to its new position.
When releasing the button, blue springs push the pink and orange bars and their spheres force four blue wedges aside to clamp the slider thanks to friction.
The button is fixed to the bar by thread.
To ensure that all wedges always contact with the runway when clamping the cylindrical joints between the bars and the slider must have considerable gaps. For the same reason there must be enough longitudinal gap between the pink and orange bars.