The Lansinoh Breastmilk Storage Bags are equipped with a pre-sterilized interior that eliminates the need for additional sterilization, saving time and providing added peace of mind for mothers. The bags feature a stand-up bottom, making them easy to fill, and they are able to stand upright in the freezer or fridge, allowing for optimal storage and organization. The flat design of the bags also saves space, allowing you to easily store several bags without taking up much room. Each bag has a write-on labeling area, which enables you to record the date and time of pumping, ensuring proper rotation and usage of milk, preventing waste.