c. 1975. Complete set of five rings in a set issued by Stan Toy Co. The ring bases are of iodized aluminum w/bands that expand. Examples seen here include Galen, Zira Dr. Zaius Urko w/black finish and Cornelius w/finish in gold luster.  The character images are on paper stickers and because of the nature of the adhesive on the underside there is aging to the bkg. areas, and does not affect the portrait areas. NM/Mint.
 
Individual rings in this set are rare, a full set being very rare.
 
A set with the original display box sold on HAKES AUCTIONS in 2013 and this box is extremely rare, being the only example I have seen.