Flexi-bags (also flexibags and flexi-tanks) offer an alternative to ISO tank containers for shipping oils, juices, wines, food-grade liquids and nonhazardous chemicals across the globe. Flexi-bags are usually loaded into 20' food-grade, ISO containers for maritime or rail transport. Sizes range from 16,000 to 26,000 litres. For transport in the US, the materials used in the production of flexi-bags must meet the US Food and Drug Administration, EU food-grade or German BAG standards. The idea is to isolate the liquid being transported from ambient air to avoid oxidation. 
They can also be used to transport a variety of other liquids such as base oils.
Depending on the product, many ISO tank container operators argue that flexi-bags can be more costly and less environmentally sound. This is generally the case for higher value products and/or environmentally dangerous products, because the transport protection offered by a flexi-bag is less, and the level of product that is left in the flexi-bag (2 to 5%) is higher than the amount left in a tank container.