The 2026 S U. Mint Clad Proof Semiquincentennial Set is a commemorative coin set minted by the United States Mint in San Francisco. The set includes various denominations of coins with a copper-nickel composition and a fineness of 0.999. The coins are struck in proof condition, making them highly collectible for coin enthusiasts. This set celebrates a special milestone in American numismatics and is a valuable addition to any coin collection.