The Bosch Rexroth Z2S6B1-6X/ (R900347501) is a pilot-operated check valve in a sandwich plate design. It is used for the leak-free blocking of one actuator port, which is particularly useful for applications like holding a hydraulic cylinder in position. This valve allows free flow from channel B2 to B1 while blocking the flow in the opposite direction. The blocked channel can be opened by applying sufficient pilot pressure to the opposite line (channel A). Designed for vertical stacking assemblies, it is typically installed between a directional control valve and the subplate. This model features the check function in port B with a cracking pressure of 1 bar.