Returning to work does not mean stopping breastfeeding for your child. By expressing milk, the baby can still get milk without the mother next to him. In addition to the milking pump and the bottle of breastmilk storage, there is one more 'weapon' that mothers should want to continue giving breastfeeding while working, which is a breast milk cooler bag. Now breast milk cooler bags have been sold in various colors, motifs and shapes. The breast milk cooler bag is usually protected by a layer of insulation or styrofoam which can prevent outside air from entering so that the temperature inside the bag is maintained. Thus, breast milk will also be protected. A good breast milk cooler bag is generally made of three types of materials, namely a cold temperature barrier layer, a waterproof layer, and an outer layer. A good waterproof coating is generally in the form of laminated cotton, PUL, or vinyl plastic. While the outermost layer is the same as the waterproof layer or it can