Mount these valves onto compressed gas tanks. Also known as Schrader valves—which are typically used with compressed air—they have an internal spring that holds the valve shut when you depress the pin to add, remove, or check the pressure of compressed gas. Made of brass, these valves thread onto nuts more easily than valves made of harder metal. They also have good corrosion resistance. Valves have a thread cap to protect the stem from accidental gas release.