Abstract: A cap for a gas pressurized container, adapted to maintain the pressure therein. The cap includes an insert which forms a seal between the exterior surface of the insert and the opening in the bottle. Disposed inside the insert is a valve which forms a seal between the interior of the insert and the interior of the bottle. A spring urges the valve away from the interior of the bottle to a closed position. The valve is opened by depressing a button on the outside of the cap. The gas pressure in the container urges the valve outward to perfect the seal. The cap may be used in any context wherein a gas tight seal is desired.