Abstract: A bottle includes a container and a closure device. The closure device includes a threaded cap for closing up the container, a slidable spout for opening and closing the fluid flow path from the container by means of two sealing elements on the spout, a vent check valve for permitting air to rapidly enter the container without passing through the spout and a multi-fold protective cover and, more particularly, to a two-fold protective cover for achieving the leak-proof by forcing the spout to a close position and closing up the vent check valve by a projection extended from the protective cover.