The Hydro Flask Bottle Boot is a durable silicone Flex Boot that lets you customize the look of your Hydro Flask bottle and protect it against bumps and dings. The colorful small flex boot fits 12-24 oz wide and standard mouth bottles. This removable, silicone boot adds extra protection to your Hydro Flask. It is BPA-Free and comes with a lifetime warranty. The grippier base helps in preventing accidental spills.