Abstract: A rotatable knob mounted at one side of an opening to a container has formed on the underside thereof a recess and a channel extending therefrom through the periphery of the knob. Opposite the knob on the other side of the container opening is secured a clasp. When the knob is rotated into its open position with the catch channel directed toward the catch, closure of the opposite sides of the container opening moves the catch through the catch channel to the recess on the underside of the knob. Thereafter, rotation of the knob in either direction out of its open position, captures the catch in the recess on the underside of the knob. Release of the catch is accomplished by rotating the knob back to its open position. In an alternative embodiment, the catch channel terminates short of the periphery of the knob, but a portion of the knob extends beyond the edge of the container opening.