  Old light meter. 
This is one of a batch of three old photographer's light meters I got on eBay: From the paperwork that came with them, it looks like people sent them in for repair at a certain shop, paid for the repairs, but never claimed the meters.  That was 30 years ago, so I guess the shop can be forgiven for giving up hope on them. 
The neat thing about selenium light meters is that they require no batteries: The selenium sensor works like a photocell to generate its own electricity.  This meter, having been repaired only 30 years ago, works perfectly. 
Source: eBay seller beaglemania2 
Contributor: Theodore Gray 
Acquired: 15 August, 2003 
Price: $7 
Size: 4" 
Purity: <10%
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