If your bottle has a milky hue, it is made of polypropylene (PP), a BPA-free material. Philips AVENT bottles made of this material come with an additional adapter ring to ensure the unique skirt on the teat always fits the ring of the bottle, guaranteeing the anti-colic feature.
If your bottle has a natural honey-colored tint, it is made of polyethersulphone (PES), a BPA-free material.
If your bottle is clear, it is made of polycarbonate (PC).