The 1999-S US Mint Silver Proof Set includes 9 uncirculated coins with a silver composition of 90% and a fineness of 0.900. Minted in San Francisco, these coins bear the strike type of proof and come with a Certificate of Authenticity from the U. This set is a valuable addition to any coin collector’s portfolio, showcasing the craftsmanship and quality of United States silver coins from the late 20th century.