Under normal circumstances, the fund invests at least 80% of its net assets in U.S. Treasuries that have a remaining maturity of seven to ten years and investments that have economic characteristics that are substantially similar to the economic characteristics of such Treasuries. The index is composed of fixed-rate coupon U.S. Treasury securities maturing in 7 to 10 years or with remaining maturities between 7 to 10 years.