Abstract: The invention provides a check valve for a test point for taking pressure measurements or fluid samples in a pressurized fluid system, said check valve including a housing having a bore and a movable valve body located in said bore, one end of said housing adapted to receive a pressure measuring probe for taking said pressure measurements or fluid samples, said one end of said housing including an upper bore section within which, in use, said pressure measuring probe is located wherein said movable valve body includes an end, located in said upper bore section, of nominal diameter less than the nominal diameter of said upper bore section.