This is your personal cup holder - never again do you grab the wrong bottle, like the one your seasick buddy just had his gross lips all over. It doesn't get any simpler than this - a single cup insert held to a vertical surface by a powerful-yet-simple-to-use SeaSucker 4.5 Inch vacuum mount. The cup holder insert removes for easy cleaning and can be swapped out for one of our Small Dry Boxes, which effectively turns this into a convenient holder for your cell phone.