Medela's wide range of PersonalFit breast shields allows mothers to choose the breast shield that is the right size for them, to ensure maximum comfort and efficiency when pumping. Designed for individual maximum comfort, personalised breast shield size for most comfortable pumping, maximum output, optimised breast emptying. Made from 100% Bisphenol-A (BPA) free materials for the health of your baby. The right breast shield size and a proper fit avoid compression of any milk ducts during pumping. As a consequence the mother is given the best chance of protecting of her milk volume, optimising breast emptying, preventing nipple trauma and pumping with comfort. This will help a mother to maintain her milk production and support her lactation. Using a too small or too large breast shield may lead to impaired milk removal because milk ducts could get blocked or milk ejection inhibited. Over time, this can result in reduced daily milk output, which will decrease milk production and can lead to early weaning. Friction around the nipple and/or areola can cause discomfort and trauma which may cause a mother to only pump infrequently. Again, her milk production is jeopardised. Tissue breakdown due to nipple trauma carries the risk of infection and mastitis. The bespoke design of the Medela PersonalFit Breast Shield ensures breast-pumping remains a safe, enjoyable experience that will protect you and your baby for the long term.