A closure cap (10) is provided with an audible warning when the cap (10) is removed from a container (12). The closure cap (10) preventing the inadvertent consumption of pharmaceutical products, bleaches or other products by children or other minors. In use, the closure cap (10) may be provided with child resilient means and can be screwed on to any standard container (12). When the cap (10) is removed from the container (12), mechanical energy is expended by the user and such mechanical energy is converted to sufficient electrical energy using a piezoelectrical element (14) contained in the cap (10). The electrical energy generated is then conditioned and stored using signal conditioning electronics (26) such that and alarm signal of sufficient level is sounded. In use, the piezoelectrical element (14) is interposed between two sprung steel sections (16) formed as a dome and the action of unscrewing the cap (10) causes the sprung sections (16) to snap back producing a large dynamic force on said piezoelectrical element (14) which produces a large voltage output.