If you have ever traveled or climbed a mountain, you know that extra room in your backpack counts. You probably always regret that you put an empty flask into the backpack since it takes up so much room. That is why we designed a flask that collapses. It takes as much space as a small notepad and extends when it is filled. As the flask becomes empty, it adjusts the size and becomes smaller. The flexible walls allow you to use the space in your traveling bag more effectively. The Collapsible Flask is stylish and hip. Ideal for those who want to travel with comfort. Available in three colors.