The Seachem Just Add Water Jug is a incredibly durable water jug designed to transport and store freshwater, saltwater, reverse osmosis water, or deionized water for aquarium applications. The jug is constructed for maximum user convenience, featuring an extra wide 2.25 inch diameter opening with an additional air outlet for easy, hassle free pouring. The jug is completely BPA free and is made of 100% plastic, ensuring that no harmful chemicals leach into your water supply.