The NUK orthodontic shape adapts to the baby's mouth area & helps exercise the lips, tongue & facial muscles for healthy development of teeth & jaws. The NUK Air System helps to ensure the mouthpiece remains soft & flexible. The NUK orthodontic shape & NUK Air System have been approved by the British Dental Health Foundation. Soother has integrated circulation grooves so air can circulate avoiding skin irritations on baby's sensitive mouth area. Starlight's special flat rounded shape helps prevent pressure marks whilst baby sleeps.