These silicon teats mimic the shape of the breast enabling baby to feed naturally with the feel of natural nursing fitted with a system to ensure air stays inside the bottle rather then being taken into babys stomach minimising the risk of swallowing air which can lead to painful colic 5 different designs for each use size 1 suitable from birth size 2 from 1 month size 3 from 3 months size 4 from 3 months variable flow size 5 from 6 months