Bell & gossett model sb-3/4" sweat, combination straight or angle-pattern flow-control valve. Its ductile iron body is rated to 125 psi and 250 degreef. Flo-control valves prevent gravity flow in forced water systems and permit operation of indirect water heaters during both summer and winter. With a pressure drop of 1 to 7.5 feet of water this valve will perform from 1 to 125 gpm. See performance curves for your exact flow rate.