The Dr. Browns Natural Flow Microwave Steam Sterilizer Bags sterilizes parts from Dr. Browns baby bottles, eliminating 99.9% of most household bacteria and germs. They are designed to fit all Dr. Browns baby bottle parts, and they are perfect for steam cleaning while on-the-go or while traveling. Five sterilizer bags come to a pack, and each bag is reusable – up to 20 times. This offers moms 100 uses per retail pack.