Rappel - the smart smoke detector. We made the Rappel because most smoke detectors flash or beep when low on batteries. Due to their high location on ceilings, it makes it difficult to change the battery. We wanted to make an intuitive smoke detector that reminds you when the battery is low and makes it easier to reach. Our smoke detector automatically lowers itself on a cord when the battery requires replacing, and ascend back when the new battery is in place.