The magic Avia spinner of the Zlin.
This spinner freely moves, independant from the propellor, driven by the vanes. It drives a hydraulic pump inside. If you press on the 'don't push here' you'll see it actually moves.
During flight, the air pressure (depending on the airspeed) on the spinner operates a valve. This valves regulates the pitch of the prop.
Thanks to the owner for explaining this nice piece of engineering. Clever system isn't it?