Pat's been hanging around the medical supply house again. We now have a boatload of rubber stoppers, the kind you see on bottles of liquid medicine, crimped down with an aluminum collar. (Pat didn’t buy the aluminum collars.) The medicine is removed via a hypodermic needle through the stopper. The rubber stoppers come in a friendly orange and fit (13 mm) dia openings. The orange are 9/16" across the top, which has a dimple in the center, and 9/16" top to bottom. Why would you want them? Because they'll fit many of the small wide-mouth and slope-shouldered bottles in our Bottlemania listing. Pat's really good!