I've been using Tattlers for 6 or 8 years. If you do it right, they'll seal all the time and will stay sealed as well as any metal lid. Have you ever seen antique canning jars with glass lids and a flip wire to hold them in place? They used rubber rings like the Tattlers and they were used for many years until the metal lid was invented. It's all in getting a vacuum inside the jar. Air pressure holds the lid on no matter what kind you use. Tattlers rings are thicker rubber than metal lids and should fill up the gaps better to hold the lids on.
