The MFS Maryland Municipal Bond Fund Class B (MBMDX) is a mutual fund that primarily invests in municipal bonds issued by the state of Maryland. 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, tax-exempt municipal bonds. As a Class B fund, it may have higher fees and expenses compared to other classes of the same fund. Overall, MBMDX offers investors a way to support the development of Maryland communities while potentially earning a steady stream of tax-free income.