Secure, Leak-proof Double Zipper Seal: The bags feature a secure, leak-proof double zipper closure, ensuring safe storage of your breast milk without any risk of leaks or spills. Pre-sterilized with Tamper-proof Seal: Each bag is pre-sterilized and comes with a tamper-evident seal, ensuring that the bag is untouched before first use, thus maintaining complete hygiene. Freezer-safe with Reinforced Seams and Dual-layer Bag: The bags are freezer-safe and feature reinforced side seams and a dual-layered material, providing extra reassurance that your breast milk is stored safely in the freezer or fridge. Wide Opening for Easy Filling and Pouring: The bags have a wide and sturdy opening, making it easy to fill and pour your breast milk without any spills or mess. Self-standing Design: The sturdy design of the bags enables them to be self-standing, allowing for easy handling and filling. Flat Storage: The bags are designed to lay flat for easy storage in the freezer or fridge, optimizing space utilization. BPA-free Material: The bags are made of BPA-free material, ensuring the safety of your breast milk. Overall, the AVENT Breast Milk Storage Bags offer convenience, safety, and reliability for storing your precious breast milk. With their secure seal, pre-sterilized design, and freezer-safe construction, they provide peace of mind for nursing mothers who want to safely store their breast milk for later use. (description exceeds maximum possible length)