What is a Plug Scope??!

Got this out of my great-uncle's garage a few years back. It's before my time, so can anyone tell me what it is an how it works??

~Chris

 

it's discussed here?

http://www.jalopyjournal.com/forum/showthread.php?t=72526

 

Cool, I want it!

 

Ok, you take that...I want the fridge.

 

Hahaha glad u like the fridge, it was my great grandad's. My mom says she remembers it from when she was a little girl. Still works good as new!! It's my garage fridge.