Avent ultrasoft breast shells can be worn inside your bra to protect your nipples from chafing and to collect leaking breast milk. The ventilated shells protect sore or cracked nipples to help them heal more quickly and the gentle pressure they produce helps relieve engorgement. The holes allow air to circulate. The Breast Milk Saver Shells (no holes) - collect leaking breast milk when feeding or using a breast pump. There are 2 shells per pack.