The Spectra Disposable Milk Storage Bags are BPA-free and pre-sterilized. Each bag holds up to 200 mL and features an easy-to-read measurement scale. The zip-top seal allows for long and safe storage in the fridge or freezer. The Spectra Disposable Milk Storage Bags are double-lined, providing a sturdy and spill-proof structure. Each Spectra Disposable Milk Storage bag will stand upright when filled with breast milk, allowing accurate readings from the measurement scale. After filling a milk bag, Spectra highly recommends labeling each bag with the correct date of use which is located on the front. It's important to remember to leave at least 1 inch of the baggie free from milk when storing bags in the freezer as breast milk will expand as it freezes. This pack of Spectra Disposable Milk Storage Bags includes 30 sterile breast milk storage bags. PLEASE NOTE: These are for storage use only. You will require an adapter to pump directly into the bags. The adapter is not included.