These ultra soft breast shells are worn inside your bra to protect your nipples from chafing and to collect leaking breast milk. Ventilated shells - protect sore or cracked nipples to help them heal more quickly. Their gentle pressure helps relieve engorgement. The holes allow air to circulate. Breast milk saver shells - to collect leaking breast milk when feeding or using a breast pump.Each set contains: 2 x ventilated shells 2 x milk saver shells 2 x ultrasoft silicon backing cushions.