Pigeon's original nipple design. Research conducted on baby's oral development shows that baby suckles breastmilk by moving their tongue in a smooth, wave-like motion. This is called 'Peristaltic motion' and is the natural way a baby feeds. Pigeon teats have been designed to mimic and promote this natural sucking action. Pigeon teats will reduce nipple confusion between breast and bottle.Sizes Suitable for slim necked bottles. S size is for newborns to around 3 months+ and has a round hole at the teat tip. Suitable for slim necked bottles. M size for babies 4 months+ and has a round hole the teat tip. Suitable for slim necked bottles. L size for babies 9 months+ with a round hole at the teat tip. Suitable for slim necked bottles. 'Y' size teat is a variable flow, cross-cut teat which opens depending on how hard the baby sucks, so it can be used from birth ongoing.