Very nice example of an Übertrager, which was a device for field phones to convert between single and double line connections. The Preßstoff case is a very nice and quite clean example. This is a piece from my own collection. It is one of the best examples I have seen in a while. I am only thinning it out in favor of one which is in more rough condition that I will not feel guilty taking out and using. This is one for the display and collecting.