This Philips Avent Natural bottle is made of premium PPSU, a BPA-free material. Known for its golden color, PPSU gives you both comfort and durability. PPSU has high heat resistance (up to 180°C/356°F), similar to glass baby bottles, while still being lightweight.  The Natural Response nipple with the unique opening and tip lets your baby control the pace of the milk flow, releasing it only when actively drinking - just like babies do during breastfeeding. When pausing to swallow and breathe, no milk flows. Feeding feels as natural as from the breast! Easily combine breast and bottle feeding with a wide, soft, and flexible nipple that mimics the shape and feel of a breast. It helps the baby to latch on and feed comfortably, using its natural rhythm. With the no-drip design, the nipple helps prevent spills and lost milk. An anti-colic valve integrated into the nipple is designed to reduce colic and discomfort by sending air away from your baby's tummy. The ergonomic shape makes it comfortable for parents to hold. Assembly is simple with only a few parts and the wide bottleneck makes filling and cleaning easy. It is totally natural for your baby to take 2-3 tries to get milk flowing from a new bottle. We have 5 different nipple flow rates - when looking for the right one, age is a guide, but your baby's approach to drinking and the feeding cues will help determine when to move to a higher or lower nipple flow rate. ¹ the PPSU container is heat resistance up to 180°C (356°F)/ 356°F (180°C) ² more durable than PP baby bottles, lighterweight than glass baby bottles