These silicone lid inserts / liners are leak proof, food safe, and dishwasher safe! They are designed for white plastic Ball storage caps), Mason Jar Lifestyle plastic storage lids, and MJL stainless steel lids. They also work with many of our decorative lids, and lots of others. They now feature a pinch tab near the edge to make them much easier to remove! The tab should go down, into the jar. When used with a band alone, they work best with the tab up. Made of platinum cured silicone rubber, these lid inserts are dishwasher, freezer, and microwave safe! Silicone is a safe, green, non-plastic (BPA free) material that does not leach any chemicals like plastic can. Platinum cured silicone is more expensive and more pure than peroxide cured silicone. 10 platinum silicone discs per order. They are made of clear, food grade, BPA free, platinum cured silicone rubber. The regular mouth size are 70mm in diameter and 2.7mm thick. The wide mouth size are 86.5mm in diameter and 3.3mm thick