Medela contact nipple shields can be an effective tool for professionals and moms to manage infants with latch on problems, for moms with overactive let downs or for flat, inverted and sore nipples. Medela nipple shields enable continued breastfeeding without interruption until these problems are resolved. Special design for closer contact with baby. Available in different sizes (16 mm, 20 mm, 24 mm) consult with a lactation professional for assistance. Made without BPA safe for mom and baby. All Medela breastmilk bottles and products that come in contact with breastmilk are and always have been made without BPA.