These were sold by both Supreme Magic Company and Roy Baker c. 1970, but I believe they were originated in Germany. Based on an even older principle.
As much as I hate to say it this set were actually made by Magic Makers, but they are nicely made and are a great effect that I wanted at least to acknowledge on my site.
Effect: Two flat square plastic plaques are shown. On one side of one plaque the five spot side of a die is shown. On the reverse side it shows a two spot. The other plaque shows a four and a three spot respectively. With the spectators eyes glued to the performer’s hands he takes one plaque in each hand. It does not seem possible, but the Las Vegas Dice change places. The spectators cannot believe their eyes when the performer offers to repeat the effect and places one of the plaques in his pocket whilst the other is left in his hand. The hand is opened and the one that has just been placed in the pocket is in the hand. Spectator removes the one from the pocket and to his amazement it is the one just placed in the hand. A GREAT POCKET ITEM.
(Notice: Includes: Printed Instructions.)( Post Source: martinsmagic.com - click for details )