The Z2S10 series pilot-operated double check valve is a specialized unit for closing a one-way oil flow, and opening path for the opposite direction. This assembly is generally used to ease a working circuit under pressure, to avert a load from falling in case of line rapture, and to eliminate irregular movement of a hydraulically suppressed system. It is normally integrated as a transitional components between the regulating valve and a sub-plate. An O-ring unit is incorporated as a major sealing tool. Its simple construction permits installation at any position possible.