This double-sided lid is a genius way to bring food and beverages on-the-go! It keeps both jars securely connected together so they won’t clink together in your bag. Fits any size Regular Mouth Mason jars, which are 2 3/8″ internal diameter. Leak-proof with included silicone seals. Upgrade to full silicone liners so your food doesn’t touch the BPA-free plastic. One lid and two silicone seals per order. Jars not included. Connect any 2 regular mouth Mason jars – mix and match any sizes. Widely available in 4oz, 8oz, 12oz, 16oz, and 32oz. Think carefully when you open it so you don’t unscrew the jar that is upside down 🙂 Made of polypropylene, which is a BPA free plastic. Included silicone seals are FDA food grade, or upgrade with 2 full liners that cover the entire inner surface (they don’t fit perfectly, but well enough to be leak proof).