The Contigo Shake & Go Fit Protein Shaker 720 is more than just a convenient bottle for your smoothies. This bottle has a hidden storage compartment for your bank cards or keys, for example. Now you won't need to carry them separately when you go to the gym. The bottle also contains a ball, and for good reason. When shaking the bottle, the ball makes sure the ingredients mix better and prevents any lumps. Do you dislike the hassle of always having to weigh the ingredients before putting them in the bottle? The volume marking will help you with that, and tell you how much you're drinking.