No Smoking - Oxygen In Use (with No, PVC Vinyl Door Hanger, Pear Shaped, 4 Tags / Pack, 5" x 8.875" This specific message has a wide variety of uses, great for almost any facility. Each tag hanger fits right over a door knob or valve. A grease pencil or a permanent pen will let you add an explanation directly on the tag. Message is printed on both sides of tag.