The plastic mason jar lids that are available do not create an airtight seal with the top of the mason jar. This means that liquids will leak out or dry out and dry goods will go stale when stored with these lids. The flat seals that are available try to cling to the inside of the lid and don’t always stay there. These can fall out when you are trying to put the lid on the jar or when taking the lid off. So, we came up with the idea of creating a seal that sits on the rim of the jar. This unique design cannot fall off the lid or into the jar. It is easily and quickly placed on the rim of the jar and then the lid can be tightened down. Because our seal is design to fit the rim of the jar and not the lid, it will work with any plastic lid out there. We want our seals to be durable so we molded them out of 3/32” thick, food-grade compliant silicone. Please note that these lids are for storage only and cannot be used for canning. Also, these seals do not work well with metal lids.