From the Ceres Chill website: The patented Ceres Chill Chiller is rigorously lab-tested to provide longer and more reliable chilling than any other on-the-go breastmilk storage solution. No power cords, chargers, or fridge Always have everything you need to keep your breastmilk chilled: Our Chiller relies only on a splash of water and a handful of ice cubes — things you can refresh easily when you need more chilling time. Verified purchaser Renee, who loves science as much as we do, independently documented how well this works. Pump directly into the Chiller Pumping directly into your storage container greatly reduces the risk of spilling or contaminating your precious milk. And the Chiller parts are designed to support double-pumping with no extra bottles. Airport and travel friendly