The DORNA DS1P-04AS is a high-performance modular pilot-operated check valve designed for reliable operation in hydraulic systems. This valve allows free flow in one direction while blocking flow in the opposite direction. The reverse flow can be opened by applying pilot pressure to the pilot port. Its modular, sandwich-plate design conforms to the NG6 (CETOP 3 / D03) standard, allowing for easy and compact stacking with other directional control valves, which simplifies circuit design and reduces the need for extensive piping. Built for durability, the DS1P-04AS is ideal for applications requiring secure load holding, such as in presses, machine tools, and mobile equipment.