Single shut-off. 5/16" (7.9mm) Inside Diameter. Connecting and disconnecting your fuel line in a split second. Press the thumb latch and the coupling halves disconnect. The half with the thumb latch is equipped with an automatic fuel shut-off; the other half will stay open. Use dual shut-off for tanks with a crossover line. To connect the fuel lines; just press the coupling halves together. Comes with Viton O-rings. Can be used with any type of pump gas or racing fuels. Note: See 960476 for replacement 5/16" O-ring