I was asked to review a recent purchase of a #3 White Silicone Rubber Stopper. Based upon my experience with stoppers, this was the best one I've procured to date. It was as described in the WIDGETCO specification and fit my application perfectly. While I have not confirmed precise material properties of the silicone, I can say based upon experience that the temperature range meets and may exceed the needs of most cooking processes e.g. 400 degrees F. I certainly will consider WIDGETCO for any future stopper needs.