Thermal efficiency and ergonomic design. Isothermal double wall structure: Double-wall construction keeps water cold twice as long as regular sport bottles. Cap with soft push-pull tip and protective cap. CAP: Copolyester resin – taste your beverage and not your bottle. Cap can be completely removed for better cleaning and fill up. Wide-mouth opening is easy to fill with ice and water and a breeze to clean. Bottle body with easy-squeeze polyethylene. Regular Hi-Flow of liquid. Lightweight, easy-squeeze bottle delivers the right flow to quench your thirst. Ergonomic grip. We don’t recommend heating the bottle in a microwave since contents can heat unevenly. We don’t recommend putting boiling liquids in the Hot & Cold Bottles. Complies with food contact regulations.