The MFS Pennsylvania Municipal Bond Fund - Class I (MPALX) is a mutual fund that primarily invests in municipal bonds issued by the state of Pennsylvania. These bonds are issued by local governments and are used to fund public projects such as schools, roads, and utilities. This fund aims to provide investors with tax-free income and potential capital appreciation through its investments in high-quality municipal bonds. As a Class I fund, it is designed for institutional investors and may have lower fees and higher minimum investment requirements compared to other classes of the same fund.