This is a one-of-a-kind item, an original German Gossen Luna Pro electronic exposure meter - the top of the line in its day. It still works perfectly and comes with the 30 page original owner's manual (in English). Very detailed instructions on the meter and all its capabilities. The retail price in the 1970s was $75 - easily the equivalent of hundreds of dollars today.
It comes with its original leather case which is also in excellent condition. Meter requires two Mallory PX 625 or PX 13 batteries or WeinCell MRB625.
This meter will read the moonlight - hence its name. It reads reflected and incident light.