The 21-ounce insulated water bottle is one of Hydro Flask's best-sellers for its standard size and versatility. It fits perfectly in the side pocket of your backpack or in your car’s cup holder, making hydration always within reach. The Flex Cap securely closes to prevent leaks and spills while on the go, and the standard mouth width offers easy sipping without spilling. A professional-grade stainless steel exterior with Hydro Flask's patented TempShield insulation keeps your cold beverages cold and your hot beverages hot, from first sips to last drips. Enjoy staying hydrated, with Hydro Flask's 21-ounce insulated water bottle. BPA and phthalate free for clean hydration TempShield vacuum insulation preserves beverage's temperature for 12-24 hours Secure flex cap prevents accidental leaks Mid-sized for versatility and everyday use Summer 2023 product Equipped With TempShield TempShield is Hydro Flask’s innovative double-wall, vacuum insulation, which protects the temperature of its contents and eliminates condensation. TempShield keeps liquids cold up to 24 hours, and hot up to 12 hours.