Our excellent performance is largely due to the patented design and quality of materials used. The design of the Revomax lid has a double seal, with the first seal focusing low in the neck of the flask where it is vacuum insulated. This ensures there is a temperature compromise through the wall. The second seal is focused on the top lip of the flask. This seal creates a chamber in the neck of the flask, adding insulation between your beverage and the outside influences of temperature. The high-quality food grade silicone seal is designed so both seals have a constant state of connection, ensuring two perfect seals working together. With traditional thread lids, the neck of the flask has no insulation. This method causes temperature migration through the wall and thread