DESIGNED/MANUFACTURED: To exacting standards. This is a Closed/Sealing-type air chuck for use on a compressed airline. DUAL HEAD CHUCK: Makes tire valves more accessible with the two heads for easier access. INFLATE: By hooking the closed head (w/valve) directly to an airline. EASY ACCESS: To inner dual when valve is facing inward. Great for reaching into Dually trucks and other challenging angles. MAX PSI: Maximum air pressure of 150 pounds per square inch. 1/4" female national pipe thread.