Medela - Valve Head
One pale yellow valve with offset mount The yellow valve fits snugly onto the base of the breastshield connector, and holds the white membrane in place.
(Medela no longer makes the yellow valve with center mount).
Care of the yellow valve.
The yellow valve should be removed from the breastshield connector after each pump use. The white membrane should be removed from the yellow valve and both parts cleaned. If these parts are not cleaned milk will likely be trapped between them leaving the white membrane sticky. This will prevent the white membrane from moving properly during pumping and decrease effectiveness of the pump.