DI-77/ID-11 Dosimeter

Here's a little 1 i found on e-bay, i only could not find the reading station. (will try to find 1)

There is a measure device for it but i still haven't found it and i don't know how it works or to zero the dosimeter, i contact the seller but no answer till now.

The device is called CDI-77 unit (thats what the seller says)

The 1 i have is also 1 of the early made meters as it has a low number.

My guess is this is similar to the dial-window device where the active window gets darker with exposure, and the missing measurement device here is either a light source and meter that displays the 'darkness', or a set of comparison windows.

The seller says it's working with UV to read the exposure, but i don't know for sure untill i found the Poland or the Russian device (CDI-77/DPP-32)
They also say it's a replacement for the DKP-50 dosimeter.