The Bosch Rexroth R900503669 FD 12 PA21/B03V is a high-performance throttle check valve designed for precise control of hydraulic fluid flow. As a sandwich plate valve, it is engineered for easy installation in vertical stacking systems, typically between a directional control valve and its subplate or manifold. This model provides meter-in control in the P-line and meter-out control in the A-line, allowing for fine adjustment of actuator speed in one direction while enabling free, unrestricted flow in the opposite direction via an integrated check valve. Built for reliability and durability, it is a key component in hydraulic systems requiring accurate speed regulation.