Medela Breast Milk Cooler Set, 5 oz. Breastmilk Bottles with Lids, Cooler Bag, Contoured Ice Pack What a "cool" idea! The Breastmilk Cooler Set is great as an extra set for bringing to work or school to store pumped breast milk or for leaving at daycare with your baby. The contoured cooling element is designed specifically for your Medela breast milk bottles.