The 2006 US Mint Clad State Quarter Proof Set includes a collection of uncirculated 25-cent coins struck in cupro-nickel at the San Francisco Mint. Each quarter features a proof finish and comes with its original box and Certificate of Authenticity from the U.S. Mint. This set is a valuable addition to any coin collector's portfolio, showcasing the intricate designs and craftsmanship of American state quarters from the year 2006.