Silver is a natural antibacterial, anti-fungal and antimicrobial metal. It also has anti-inflammatory properties, so using them on your nipples between feeds supports healing and prevents infection. Because breastmilk doesn't only come out when you want it to, these cups often hold a little milk in them while you're wearing them and maintain milk contact, which, as many midwives will tell you, is one of the best things you can put on your nipples to promote healing. Double win. The ventilated design ensures maximum wearability and the cooling silver gives instant oooft after feeding.