From APMEX: The coins in this set were designed in 1975. 4,974 sets in proof were made by the Franklin Mint. The combined silver content of the silver pieces of this set is 5.694 oz. Interestingly, at the time of this issue, this set contained both the largest and the smallest circulating coins in the world. This set includes the original certificate of authenticity and comes in the original case of issue.