Genuine Hydro Flask custom parts! Popular color! Small Flex Boot Color name: Trillium For 12-24oz bottles. *Please note that it does not fit 32oz bottles.* Attaching it to the bottom of your bottle protects it from dents, scratches, and dirt if dropped. You can also express your individuality by matching it with your favorite colors. It's also fun to see new colors released every year! It's also fun that you can't get the previous colors when new ones come out!