I hate it when I catch on to something way later than others. However, according to a totally informal survey at Slate.com "approximately 0 percent of the American population is aware of the existence of these tabs." I agree. I found these tabs by accident. I am always searching cardboard-ed goods for "box tops" to donate a whopping 10 cents to my daughters school. That's when I saw the little perforation and "voila", new knowledge.  These "end locks" hold foil, parchment paper and plastic wrap in place so you can tear it, efficiently. Well, hot damn!!!