N series is with integrated EPS (Expanded Polystyrene) as the thermal layer,which can maintain chilled at 48~72 hours. These shippers are pre-qualified systems offering 2 to 8°C temperature control for up to 72 hours. Tested to a wide range of ambient temperatures, these systems give you a disposable cost-effective solution for shipping various volumes in all seasons,It is an ideal solution for safe storage and delivery of temperature sensitive products.