Thermal efficiency and ergonomic design. Isothermal double wall structure: Double-wall construction keeps water cold twice as long as regular sport bottles. Soft push-pull tip. Screw Cap can be completely removed for better cleaning and fill up. Lightweight, easy-squeeze bottle delivers the right flow to quench your thirst. Wide-mouth opening is easy to fill with ice and water and a breeze to clean. We don’t recommend heating the bottle in a microwave since contents can heat unevenly. We don’t recommend putting boiling liquids in the Adventure Bottles.