Nestle UltraPak® Peptamen AF™ with Prebio1™ Complete Elemental Nutrition 1000mL Bag, Gluten-free, Lactose-free The UltraPak® Enteral Closed System is a leading choice for tube feeding. UltraPak® is a flexible pouch which can hang safely for up to 48 hours and offers decreased contamination risk and reduced formula waste compared to open systems.