9mm Self-Stick-Valve from FixMyKite is the industry standard for all inflation valves, however can double as a deflation valve as well.
Fix My Kite 9mm Inflate/Deflate Valve
FixMyKite Self-Stick-Valves will stick on all bladders! Simply peel and stick to make a fast and easy repair, or stick it on any new bladder. Specially formulated Tear-Aid adhesive is incredibly durable and will stick on any bladder material or color. Everything needed to make a fast and permanent repair is included in package, fix it once, fix it right with a FixMyKite Self-Stick Valve.
Use as Inflate: The "one way" valve lets air enter whilst pumping, but won't let air escape when you stop pumping and remove the nossil.
Use as Deflate: You can either pinch the sides to let air out or you can cut the flap off the back of the valve to let air run out freely.