SPI Fold 'N Mail Stereo Viewer Cardboard Pack of 1
This handy light weight cardboard viewer folds into a plastic envelope (8"x5"/20.3 x 12.7 cm) with pressure sensitive adhesive backing for easy attachment to a book or report cover. The envelope can also be used as a convenient mailing envelop. Magnification factor: 1.5X.
While this inexpensive and convenient stereo viewer can never be seen as a substitute for one of the other SPI fold up stereo viewers, it just can not be beat for its convenience and low cost.