Abstract: A closure device includes a substantially planar body member having a rectilinear slot receiving a slide element. Provided on one side of the body is an internally threaded flange defining an inlet port and a funnel projects from the opposite side of the body terminating in an externally threaded outlet port. A pusher connects with the slide element through a slot in the planar body to move the slide element between positions occluding the channel between the inlet and outlet ports and opening the channel. The internally threaded flange and externally threaded funnel are complementarily threaded such that the flange may be threaded about the externally threaded opening of a container and the cap normally threaded about the container opening may be threaded to the outlet port of the closure device to seal the closure device when the latter is left on the container.