View-Master

View-Master is a brand-named variety of stereoscopic slides mounted on a circular card which is inserted into a viewer. Originally used mostly for scenic views, it eventually was primarily used for children's entertainment with scenes of cartoon characters and the like. Originally an independent company and later owned by GAF, it eventually became part of Mattel.

A Mattel/Google deal will produce new "21st century" View-Master cards, designed to be read by smartphones to produce 3-D virtual reality.

Links

 * Wikipedia article
 * Image of reel specs
 * Google, Mattel try to bring View-Master into 21st century