The Big Mouth 21 ounce water bottle has a double vacuum insulated wall construction that allows for hot teas, soups, coffee or other blends to remain consistently hot for up to 12 hours. Also, cold water, smoothies, soft drinks or anything you may need very cold, 24 hours of insulated confidence. Guaranteed cold, Period. The stainless steel is the purest form of material to house your liquids, hot or cold. It is free from phthalates, lead, or any other toxins that are harmful to the body or planet.