The task of pilot operated check valves is to avoid unwanted movements of a hydraulic actuator caused by its workload. A typical application is the sustenance in his working position of an arm of an agricultural machine. The release of the movement is possible by feeding the hydraulic pilot line that opens the valve. They are preferred to the overcenter valves when there is no need for control over the movement of the actuator. The VPR are single block valves. When applied to a double effect cylinder, they lock it in place on one side only. The cartridge valve VPR can be installed inside 3-way cavities dimensioned according to the SAE08 standard (3/4-16 UNF thread) or SAE10 (7/8-14 UNF thread), for recommended working flow up to 30 l/min. The maximum working pressure is 350 bar. All the valve components are made of high-strength steel and the external components are protected from the action of corrosive agents by zinc plating treatment.