Perfect For “Topping off Towables This double action pump infates and defates towables, kayaks, boats, airbeds, and other infatables. It delivers a continuous stream of air on both the up and down strokes. Simply turn the release valve counter-clockwise and you re pumping air only on the down-stroke. This is a great option when your infatable is almost full and there s back pressure. Four universal valve fttings are included to ft Boston valves and stem valves. The accordion-style hose stretches to 5 ft. long and interlocks to the pump, so that it doesn t fall off while you re pumping. Volume is 2 liters/stroke. Very effective for “topping off large towables in the boat, since peak pressure is an impressive 14 psi.