Park-Stub holder

In some parking areas in Germany, we have to buy parking stubs and place it inside the car behind the front window. Recently my parking stub turns upside down after closing the door (so I had to pay a fine).

Me and my son decided to design this little tool to fix the parking stub directly at the window. Just place the big part inside your car between the front-window (in Germany it should be placed on the co-drivers side).