BPA free. Trusted brand for 50+ years. The only bottle with an orthodontic nipple. Helps promote healthy oral development. Supports easy transition between breast and bottle. Nuk Air System helps reduce colic. All Nuk Orthodontic bottle system products are dishwasher-safe, top rack only. Instructions for use and care are not enclosed. Nuk Orthodontic Nipples have a more advanced design than standard round nipples. Feeding hole against palate: allows milk to mix with saliva and aid digestion. Angled top: reinforces correct tongue positioning. Extra-wide nipple base: mimics the shape of mother's breast. Hourglass shape: allows lips to close properly, minimizing air intake. Asymmetrical design: encourages proper jaw positioning. Nuk Air System: Vent helps reduce colic and prevent nipple collapse. Special Design Helps Reduce Colic: The Nuk Air System vents the bottle, preventing vacuum build up - this allows baby to drink continuously, swallowing liquid instead of air. Available in slow, medium & fast flow. Stimulates & Supports Breastfeeding: The nipple is shaped like mom's during breastfeeding. Supports switching between breast and bottle. Assembled in USA with parts made in USA and Germany.