This gasket set seals the joints and passages within the valve block assembly. It prevents internal and external fluid leaks between the spool housings, end caps, and the manifold body. A compromised gasket in this location allows hydraulic fluid to bypass the intended circuit, causing a drop in system pressure and sluggish or erratic actuator response. The set is manufactured to the original material specifications, matching the crush and compression characteristics required to maintain proper clamping force across the valve stack. When replacing, clean all sealing surfaces thoroughly and tighten the through-bolts in the sequence and to the torque value specified for the assembly.