NUK Silicone Nipple Shields with storage case size (L). Protection for sensitive nipples during breastfeeding. Breastfeeding is the best option for your baby, as breast milk contains everything their body will need in the first months of life to develop a healthy immune system. However, even when doing the most natural thing in the world, one can face issues; for example, the skin on your nipples may become irritated, injured, or overly sensitive.