PES

PES: Is a polymer also known as polyethersulfone which has exceptional durability, known to be less porous and less reactive than other similar  plastics.  It is a BPA-free plastic that is dimensionally stable over a wide range of temperatures, resistant to most chemicals. It can be placed in boiling water, autoclaved or steam sterilized.

Some companies are using this plastic for their baby bottles and other applications including filters.