This is a very rare engine heat control system that was used on the 190SL and pontons. It mounts in front of the radiator and needs the fabric added to it which extends the length of it.  The long cable goes through the engine bay to the driver that pulls it and adjusts like a shade controlling the heat management on cold days and starts.

You can set your restoration above others with this option from Mercedes.
The cable is approximately 86 inches long from the radiator to the ball.

All you need is replacement of the fabric and paint the metal black. There’s a small amount of fabric left on the spool to find something similar.