Question about a German optics wehrmacht

[dagger63]

Hello everybody,
I need your knowledge once please. I have an unknown look here. Who of you can tell me about this? If you look through the optics, there is no reticule visible. The good piece is about 86 cm long and it seems to me as if it is attached to a heavy device. Below is a kind of picture. Who knows advice?

[BlackCat1982]

This is one part of an Entfernungsmesser Em 0.9 m R. (Raumbild).

[dagger63]

Thanks blackcat