You need spare valves and membranes to replace the worn-out ones so that you maintain absolute hygiene for your little one. This set includes two each of Medela valves & membranes that perfectly fit all Medela breast pump models except the freestyle ones. You can easily carry these flexible parts with you while travelling with your baby. These Medela valves and membranes are made from 100 percent bpa- and dehp-free plastic that is safe for your baby. You can easily wash and sterilize them at home after every use. These extra pair of valves and membranes offer a smart way to reuse your Medela breastpump without buying a new one.