How to use this type of mucus extractor?

This looks to be a sputum trap to collect a sputum sample. The green end gets placed to your suction catheter and the white end goes to the suction regulator. There is a urinary catheter shown in the picture below which would not be used to suction sputum but you would you a tracheal suctioning catheter which would have a male end to it which would fit into the green end.