This is an incredible find!  Both the stereographic viewer and the 50-card Golf Library are in wonderful original conditiion, all things considered.

After placing a card in the viewer, you look through it and adjust the distance the card is from your eyes in order to see a clear 3-D image of Jones or Sarazen or one of the other great golfers of the time.  The back of the cards are loaded with information about the player and what to notice in the image, such as their swing or positioning, etc. 

As can be seen in the images, One of the metal corners of the viewer has been bent, turned down so-to-speak, but the viewer still fits up to the face with room to spare.  The corner could be bent back to position if done properly

This item provides a magical view back in time, to catch a glimpse of these great players in 3-D. The set is complete with all 50 cards, which show the following golfers:

Bobby Jones - 1-10   (No introduction needed)
Horton Smith - 11-14  (Winner of the first and third Masters.  Also won 32 PGA events.)
Willie MacFarlane - 15-20  (Won the 1925 US Open by a shot over Bobby Jones. They two played a second 18 hole playoff after they finished he first 18-hole playoff tied).
Gene Sarazen - 21-26   (Again, no introduction needed)
Johnny Farrell - 27-31  (Farrell beat Jones in a 36 hole play-off to win the 1927 US Open. Also had 22 PGA wins.)
Bobby Cruikshank - 32-34  (17 PGA Tour wins)
Leo Diegel - 35-37   (Won the PGA Championship twice and had 30 PGA Tour wins.
MacDonald Smith - 38-39  (24 PGA Tour wins)
Larry Nabholtz - 40-47  (2 professional wins)
Billy Burke - 48-49   (Burke won the 1931 US Open by a single shot after two 36-hole playoffs! 13 PGA Tour wins)
'The Wrong Way to Finish a Stroke' - 50