C Drone Slides Andreas Rogge

Hello, I have a question. Does anybody know or even have pictures from the C Drone slides from Andreas Rogge? Do I have to change a part of the drones when I want to tune them down or is it possible just to slide them down?
Are they stable?
Thank you very much for your help.

Best regards!!
Stefan

Being an upgrade for concert sets, I think that is only a lenghtened slide in D drones.