The Ameda Breast Milk Storage Bottles are perfect for pumping and storing breast milk with the Ameda Purely Yours breast pumps. These 4oz. polypropylene bottles do not contain BPA, and they are freezer safe. Each bottle features easy to read graduations and space for labeling with date and baby’s name. This package contains four 4oz. bottles, cap rings and sealing discs. Since the bottles have universal threading, they are compatible with most standard breast pumps and most standard feeding nipples.