The PersonalFit breast shields from Medela allow mothers the best chance of ensuring milk volume and good breast emptying whilst providing maximum comfort. The individual and personalised fit helps to prevent nipple trauma, and is convenient for travelling or for when you do not have time to clean your breast shields and need extras. BPA free, these shields are safe for you and your baby. Size conversion: S-21mm, M-24mm, XL-30mm, XXL-36mm.