NUK bottles feature improved Perfect Fit nipple, which is the same shape as Momu0026#39;s nursing nipple for the Perfect Fit in babyu0026#39;s mouth, just like Mom, so you know that your baby will love these NUK bottlesn1-piece NUK Anti-Colic Air System is built into the nipple to help reduce colic, gas and spit-up. Plus no extra parts to clean.nThe Perfect Fit silicone nipples are available in 2 nipple sizes and 3 flow rates. Size 1 is ideal for babies 0 to 6 months and offered in a slow and medium flow. Size 2 is a larger nipple for babies 6+ months and offered in a fast flow.nBPA Free. Dishwasher Safe. Leak-proof nipple sealing hood. For best results when feeding, make sure that the NUK Anti-Colic Air System symbol is under babyu0026#39;s nose so that the unique drinking hole on top side is positioned correctly.nThe Perfect Fit silicone nipple features Soft Zone that provides greater comfort for your baby as soft satiny finish conforms to babyu0026#39;s palate.nThe NUK family of brands design and develop superior products that enhance your child's overall development. By combining years of expertise and trust, we are committed to nurturing your children's healthy transitions from birth to toddler. We have worked for over 50 years to design the highest quality products that are innovative and scientifically-proven to support safe and healthy development. Backed by a dedicated team of experts, our products are designed to combine science with style while maintaining the highest quality. Our products don't just meet international safety standards, they exceed them. And we listen to the real world experts-moms just like you-to meet and exceed your needs.