Stay hydrated. - Leak proof - Matte rubber coating - 304 stainless steel - 500ml capacity - Double-walled vacuum - Aeon Athletics logo Stay hydrated. But in style. Thanks to double-walled vacuum, the Thermos flask keeps your drink either hot or cold, and is of course leak proof, so you won’t spill any of your beverage. To make sure that you will never drop it, we added a sweat free rubber coating, which assures you good grip even during most sweaty workouts.