content: We have a new home with this model installed and now 6 months later and after 2 nights of false alarms awaking us first at 3AM and then again later, these units are now removed. We examined them (clean and no dust), changed batteries and found nothing wrong...just another night of disconcerting awakening. The builder did not leave us a manuel and neither can we find one online. I'm writing this at 2:30 AM after having found these very helpful reviews...thank you!...I can go back to bed without fear except minus detectors until we purchase new ones. Do not purchase this model!