The Interpump K1 automatic pressure regulator is a manually- adjustable, pressure-operated device which, according to its setting, limits the pump/system pressure by conveying the excess of water to the by-pass. Moreover, when the outlet flow is blocked, this device totally releases the flow, thus reducing the pressure throughout the system. 250 Bar max pressure. 9-41 Lpm flow. 60°C max water temperature. Flow sensitive valve. Brass & stainless steel construction. 3/8"BSPF inlet. 1/2"BSPM outlet. 1/2"BSPM bypass. 1/4"BSPF gauge ports.