Interpump K1 unloader valve for a pressure washer pump. It is flow sensitive and will fit a wide range of Interpump pump models and other brands. Details: Maximum Pressure - 250 Bar / 3600 PSI Water Flow - 9 to 41 Litres Per Minute Maximum Water Temperature - 60°C Flow Sensitive Valve Brass & Stainless Steel Construction Inlet - 3/8" BSP Female Outlet - 1/2" BSP Male Bypass - 1/2" BSP Male Gauge Ports - 1/4" BSP Female