Check valves belongs to the category of the shut-off valves. These valves allow flow in one direction and block the opposite direction.
A check valve basically consists of a housing (casing) with integrated valve seat, a tempered and ground closing element (cone) and a pressure spring. Another design uses a ball as a closing element.
Shut-off valves from HYDAC are poppet and spool valves for the controlled opening or closing of lines and other hydraulic components.