ppsu has a far higher heat resistance than regular baby bottles, making it the safest material for your baby’s feed. these bottles are heat resistant up to 356°F without any deformation or release of toxic substances so by selecting these lightweight, ergonomic bottles for your baby, you can be confident you’ve chosen a bottle that’s nontoxic, lead-free, easy to clean, and will stand the test of time! our ppsu bottles are dependable and durable with all the qualities of glass except the breakability so perfect for high levels of usage. ppsu stands for polyphenylsulfone.