Series 2000S-M5, Hydronic, Two-Way, Universal Flow Check Valves are for use in commercial and residential hydronic heating systems to provide positive shutoff when circulator is not running, preventing flow of water to radiation units. They are easily opened for gravity circulation. Iron body construction with solder inlet and outlet connections, a combination of angle and horizontal checks, bronze seat, and brass center guide. Maximum Pressure: 50 psi (344.8 kPa).