Pigeon Peristaltic Slim Neck Teat Medium 2Pkis 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. Suitable for slim necked bottles. M size for babies 4 months+ and has a round hole the teat tip.