Your Hydro Flask is already amazing, but why not give it a little something extra? Add a splash of color and even more versatility to your favorite water bottle with this silicone bottle "boot" in olive by Hydro Flask! It's designed to slip over the base of your 12 oz. - 21 oz. Hydro Flask water bottle, so it can protect against bumps and scrapes while also keeping it more stable on slick surfaces.