1-1/4"NPT Cast Iron Universal Flo-Chek Valve.Used to Previty Gravity Circulation.Allows Use of The Heating Boiler to Maintain Domestic Hot Water In Multiple Zone Systems,Allows Circulation Only to The Zone(S) Calling for Heat Thumb Screw Allows for Manual Opening for Gravity Feed Applications.Maximum Operating Temperature:277DegF.,Maximum Operating Pressure:125 PSI,Dims:6"H X 4-3/4"W X 2-1/2"D,Weight:4.10 Pounds, Made in USA, Mfg/Box