The Hydro Flask 40oz Wide Mouth Water Bottle is our go-to for long-distance hikes, long car rides, and busy days at the office. With its whopping 40-fluid ounce capacity, it's convenient to stay hydrated during our big adventures, and with the easy-drinking, leak-stopping Flex Straw Cap, sipping has never been simpler. The water stays ice-cold in the vacuum-insulated chamber.