Cloud Height Indicator

Can anyone tell me a little about a Cloud Height Projector made by "General
Instrument Corporation, Brooklyn,NY". It says it is a ML-506A GMQ-13. I
bought one on eBay that the person thought was Hollywood searchlight, but
under closer inspection I found out what it really was. The unit is in
perfect condition and completely intact. I wanted the mirrors out of it for
use as a searchlight, but the unit is in such excellent condition, I am
finding it hard to destroy it. Is it anything that is of any historic
value, or are these things a dime a dozen?

Thanks,
Bob