The feed water pump is used to supply the boiler with fresh water. Brass nut, with stainless steel piston and ball valves.Screw fitting is 1/4 X 40 TPI. Overall dimensions are Length 54MM, width 14MM, high-95MM, weight 120G, piston diameter 7MM, travel 8MM. Is a small hand-operated, piston-type hydraulic pump used to replenish boiler water while boiler is in use and under pressure. Also used to hydrostatically test your boiler and other hydraulic applications.