The investment seeks a high level of federally tax-free income over the long term consistent with preservation of capital. Under normal market conditions, the fund will invest at least 80% of its net assets, plus any amount for borrowing, in investment grade municipal securities, the income from which is exempt from regular federal income tax. It does not limit itself to securities of a particular maturity range, however, a majority of its assets will typically be invested in intermediate to long-term maturities (3 years or longer).