The 2007 United States Proof Sets include a collection of coins with a 25-cent coin, specifically the quarters that are part of the 50 State Quarters Program. These sets are produced with a special minting process that yields mirror-like surfaces and sharp details, making them particularly appealing to collectors. The 2007 Proof Set features coins struck in high quality and is packaged in a protective case, often increasing their value among numismatists. Additionally, the inclusion of the quarter featuring the design representing Idaho contributes to the set's significance, as it celebrates state history and heritage.