Natural Way to Bottle Feed Your Growing Baby Improved! Perfect Fit Nipple Anti-Colic Air System Silicone 9/10 Babies Accept Same Shape as Mom's Nursing Nipple BPA Free During breastfeeding, mom's nipple changes shape and becomes the same shape as the Perfect Fit Nipple. Perfect Fit Nipple features Soft Zone and the NUK Anti-Colic Air System that helps reduce colic, gas and spit-up Soft Zone: Provides greater comfort as soft satin-like finish conforms to baby's palate 1 piece vent integrated into nipple - no extra parts to clean Anti-Colic Air System allows baby to swallow liquid instead of air for a comfortable feed