Bpa-Free. These Transparent Materials Are Unbreakable And Have Very Good Resistance To Heating And Sterilizing. Wide Neck For Easy Cleaning And Filling. Curved Shape: Easier For Both Parents And Babies To Hold. A Wide Teat Base With An Air Regulation Valve Encourages The Baby'S Sucking And Breathing As With Breastfeeding. Safe And Practical, The Evidence Bottles Are Guaranteed Bisphenol-A Free And Are Made From Polypropylene Or Pes (Polyethersulfone). These Transparent Materials Are Unbreakable And Have Very Good Resistance To Heating And Sterilizing.