Have a difficult time finding the right pacifier for your baby? NUK Sensitive™ pacifiers feature the original NUK orthodontic nipple shape. Invented over 60 years ago by pediatric dentists and doctors, the NUK pacifier is modeled after the natural shape of a mom's nipple while breastfeeding. This makes for an easy transition from breast to pacifier and back. The NUK heart-shaped shield fits perfectly under the baby's nose for easier breathing and prevents irritation. Now all NUK pacifiers are available in a reusable storage case that allows for easy cleaning in the microwave. (*Based on Market Research, 2017, tested with 307 pacifier users).