CIT pipe-type check valves have a ball locking element. The inverse force to the opening pressure is created by compressing the spring. Precision processing of the locking mechanism allows to reduce the fluid overflow to insignificant values. The PNEVMOLUX range of check valves will be used in various hydraulic systems, mechanisms and assemblies. The design allows the CIT check valve to be installed directly in the hydraulic system in front of the actuators, in the pipeline and other places.