For a natural drinking feeling A mother?™s nipple changes shape during breastfeeding. It adapts to the baby's mouth, enabling optimal food intake and providing the best possible training for the jaw, palate, tongue and lips. The NUK teats were therefore modelled on a mother?™s nipple during breastfeeding. NUK PREMIUM CHOICE combines the orthodontic benefits of the NUK shape with a feeling similar to breastfeeding. The following features of the bottle teat enable you to combine breastfeeding and bottle feeding without problems. FEATURES: Modelled on the shape of a mother?™s nipple during breastfeeding Orthodontic nuk shape and extra wide lip rest Available Size: Size 1 (0-6mths) S - For Thin Liquids (eg. Breast milk, water etc.) Size 1 (0-6mths) M - For Milk (eg. formula milk) Size 1 (0-6mths) L - For Thicker Feeds Size 2 (6mths+) S - For Thin Liquids Size 2 (6mths+) M -For Milk Size 2 (6mths+) L - For Thicker Feeds.