We are offering here the Bottle Gel Pack that is created by adding hydroxyethyl cellulose and vinyl-coated silica gel into the bag. This, alongside propylene glycol, will help maintain the gel pack in a state where it can be reused multiple times without failure. The gel packs are a convenient way to keep things cool for extended periods of time. The gel packs are a convenient way to keep things cool for extended periods of time. Theyre used for a variety of purposes including shipping, muscle warmth or cooling, and school lunches. The Bottle Gel Pack is very effective and safe to use.