Nuk latex teat size 1 medium feed hole is suitable for milk feeds for babies 0 6 months the nuk shape is based on scientific studies of infants orthodontic development and designed to encourage correct oral development feed hole points upwards so milk mixes with saliva for good digestion flat slender neck encourages milking action which aids babys jaw and palate development the nuk air system vent helps to prevent the teat collapsing and infant swallowing air helping to prevent colic