Leightwhight but strong tool for venting the heater (germean: Heizung entlüften).
The second version (-5) is with a knob for easier removal of the tool but otherwise identical
Note1: The position of the knob is also where you should pull to remove the tool on the first version (-4) otherwise there is a high risk of breakage due to wedge.
Note 2: recomend placing a cup below to collect the dirty water comming out the heater during use.
In case the Inventor file or a different licence is needed feel free to ask.