Abstract: This disclosure relates to a closure for a tube or bottle. The closure includes a cup-shaped cap that fits over the opening of the tube or bottle, a tubular closure member that is mounted around the cap, and a plurality of ribs that connect the cap and the closure. The cap and the closure are radially spaced and the ribs extend at a slant or pitch angle relative to a radial line. The ribs all slant in one direction when the closure is in the open or at-rest position. To seal the opening, the member is turned angularly to decrease the pitch angle, which action bends or flexes the cap radially inwardly against the tube or bottle. The member is turned sufficiently far to bend the ribs over center so that they slant in the opposite direction, in order to lock the closure on the cap or closure.