Nuk silicone nipple shields in size M are ideal for facilitating breastfeeding. This pack contains two nipple shields, designed to protect sensitive nipples and help your baby latch on. They are easy to use and clean. Trust Nuk quality for comfortable breastfeeding! Composition Silicone. Instructions for use Place the nipple shield over the nipple before breastfeeding to make it easier and to protect the nipple.