Key Features Made of high-quality LDPE and PET material, BPA free, which is environmental-friendly Pre-sterilised, very healthy to store and freeze breast milk Double leak-proof sealing strips for secure storing and easy closing and opening Self-standing bag, you could stand or flat it in the refrigerator The exterior of the storage bag is designed to conveniently record the date, time and volume of breast milk storage, the blue colored data is for clear and fast reading.