Anti-Colic Design: Prevents air ingestion, reducing colic episodes Medium Flow Nipple: Ideal for babies aged 3-6 months Soft Silicone Nipple: Gentle on baby's gums, promotes gum eruption Standard Neck Bottle: Easy to hold and use BPA-Free Material: Ensures no harmful chemicals leach into your baby's drink These 4 ounce bottles, by Nuby have a variety of fun prints with bright colors to stimulate your child's visual senses. It features our patented medium flow Nuby Nipples that are perfect for massaging your baby’s emerging teeth. The medium flow is great for milk. The bottles are made of BPA Free plastic.