Check the listing for details. 1966/1967 United States Special Mint Proof Set. Made in United States. Listed at 49.99 USD. The 1966/1967 United States Special Mint Set is a collection of uncirculated silver and clad proof coins from the United States. This set includes coins with a fineness of 0.9 and are struck in proof condition by the U.S. Mint. The set contains coins from the years 1966 and 1967, making it a valuable addition to any coin collector's portfolio. This set is a valuable and sought-after piece for collectors of US coins, especially those interested in silver coins and proof sets.