The light meter of the Rollei 35 can drain the battery if the camera is left uncased in a lit location. And if there is film in the camera you have to rewind it before you open the camera back to change the battery. That was a poor design decision but we are stuck with it. This meter shutter should help the battery to last longer, postponing the inconvenience of changing it.
The assembly should be glued together, trapping the sliding shutter, and then attached to the camera body with double sided tape.
The author marked this model as their own original creation.