Multiple nipple holes provide a natural feed, just like mom SafeTemp indicator changes color when milk is too hot Nipple comes with 3, 6, or 9 holes 5-oz. bottle has 3 holes, 9-oz. has 6 holes 1-piece Anti-Colic Air Vent reduces colic, gas, and spit up Now baby can transition from breast to bottle in a natural way with the NUK® Simply Natural™ Bottles. Designed to mimic the fit, flow, and movement of mom, 9 nipple holes imitate the shape of mom's breast while breastfeeding.