...small purple colored metal folding viewer

[DDDShelley@xxxxxxx]

Hi all, 

I recently ran accross a small purple colored metal folding viewer with about
50 stereo views that were simply 4" accross, black & white prints of subjects
all over the world with the Keystone name on them. It seemed to be some sort
of educational set? The only markings on the viewer were the words "patent
applied for". Any ideas if this is rare? What is it worth? (I found it in an
antique store, but have not bought it...)

Thanks, 

Dan {DDDSHelley@xxxxxxx}


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