Nipple First Choice: The mother breast changes shape while she feeds her baby. It fits your baby's mouth, strengthens your jaw, palate, tongue and lips. The shape of the NUK teats fit baby's mouth as does the mother's nipple during breastfeeding. Teats NUK FIRST CHOICE systematically combines the benefits of the NUK anatomical shape with the feeling of being in the breast. Get a pattern very similar to breastfeeding supply. Anatomical NUK Anti-Colic teats reduce the risk of infant colic caused by the ingestion of air through the ventilation sitema NUK Air System. Size: - Latex - Silicone +6 months - 6-18 months