The NUK Perfect Start Set contains everything a parent will need to start bottle feeding baby, and ensures to make the transition between breast and bottle easier. NUK First Choice bottles are designed to be used with First Choice teats. These teats have a specially designed orthodontic shape and extra wide lip support to simulate breast feeding as closely as possible. The NUK Air System helps prevent colic by allowing air to flow into the bottle through a vent. This ensures that no air is swallowed during feeding.