The T. Rowe Price U.S. Treasury Long-Term Index Fund I Class (PRUUX) is a mutual fund that focuses on investing in long-term U.S. Treasury securities. This fund aims to provide investors with a low-cost, diversified option for accessing the U.S. Treasury market. It is managed by T. Rowe Price, a well-respected investment management firm known for its expertise in index funds. With the ticker symbol PRUUX, this fund is easily identifiable and can be a valuable addition to a well-rounded investment portfolio.