The CMCV Series Brass Ball Check Valves are compression fittings. This series has Tube OD of 1/8 inch, 1/4 inch, and 3/8 inch. Male NPT thread sizes of 1/8 inch and 1/4 inch are available. In addition, the working pressure for the 1/8 inch tube OD is 400 psi, for the 1/4 inch it is 300 psi, and for the 3/8 inch, it is 200 psi. Furthermore, the temperature range is -65º F to 250ºF at maximum operating pressures.