Somewhat pertaining to this topic, whether your alarm was real or a false alarm.....CO is nothing to take lightly. If your detector fails and you have a high CO event.....your next of kin may be the ones telling the story. There is a saying among “preppers”.....”One is none, two is one”! Meaning, you do not place your life or well being on one item.....always have a back-up on critical equipment! We have two CO monitors in each of our units! Yes both could fail at the same time, but unlikely. We sleep better knowing that we have a back-up system! memtb