This HUNSAKER 5 Gallon QUIKFILL Fuel Jug has a stepped pour spout that starts at 2.25″ O.D. and goes up to a 3.0″ O.D. The pour spout is designed to work with either a 2.25″ or 3.0″ I.D. hose which clamps down over the pour spout opening. The full-length vent tube gripping handle has a built-in vent that allows fluid to pour quickly and smoothly. The vent also works as a 2nd fill location to fill up for your QUIKFILL.