Our breast milk bag is made of high-quality ldpe and pet material, bpa free, safe and healthy to use. it has double leak-proof sealing strips design for secure storing and easy to use. it is pre-sterilised, very healthy to store and freeze breast milk. and it is also a self-standing bag, it won't take much space. and the exterior of the storage bag is designed to conveniently record the date, time and volume of breast milk storage. such practical breast milk storage bag, worth buying!