Pigeon Standard Neck Persistaltic F/Bottle-Baby Bottle, Gender; Unisex, Pigeon's Peristaltic Nipple Is Very Soft And Designed To Be Just Like A Mother's Nipple. This Unique Design Allows The Nipple To Stretch In Response To The Natural Peristaltic Movement Of A Baby's Tongue, Just Like Natural Breastfeeding. Peristaltic Nipples Available S, M, L And Variable Flow Y Cut (Leak Proof). Exactly Like A Mother’s Nipple. Promotes Natural Oral And Jaw Development. Prevents Nipple Confusion Between Breast And Bottle. Helps To Reduce Colic.