Bottle cap with guarantee strip

In a cap for stoppering receptacles which have a neck with a threaded portion and an annular ring therebelow, the cap comprising a semi-rigid plastic one-piece body including a transverse end and a cylindrical skirt internally threaded to engage said threaded portion of the receptacle, and the body including guarantee strip means attached to the skirt and surrounding and underlying the annular ring, the improvement comprising the structure wherein:

• said guarantee strip means comprise plural arcuate strip elements each extending part-way around the ring and each terminating end-to-end with the next strip element, each strip element having near the one of its ends which leads as the cap is screwed onto the neck a first boss extending from the strip element to the skirt and integrally joining the element with the skirt and having a second boss near its other end which extends from the strip element to the skirt, and the first boss being thicker and more resistant to tear than the second boss;
• and
• each strip element having a projection extending inwardly therefrom to underlie the ring when the cap is screwed on the neck, each projection being shorter in annular extent that the annular spacing between the first and second bosses of the element whereby the bosses remain untorn while the cap is being screwed on, and each projection being shaped to underlie the ring and provide sufficient tractive force to break the second boss when the cap is being screwed off the neck.