So this is known as the pulmonary semi lunar valve or simply the pulmonary valve. Now when the ventricle when the right ventricle actually relaxes, blood flows from this location to this right ventricle. But at the same time that this valve number one is open, valve number two, the pulmonary valve has to be closed because we don't want a backflow of blood from the pulmonary arteries back into the right ventricle. But when the right ventricle actually contracts, it moves deoxygenated blood from the right ventricle into the pulmonary arteries. And valve number two pulmonary valve is actually open. So when valve number one is open, valve number two is closed.