The photoelectric sensor does the best job in detecting smoldering fires. The First Alert SA320CN Double Battery Powered smoke detector has a loud alarm so it can be heard throughout the house and responded to quickly. Rest at ease, and have the peace of mind that your home is protected with the First Alert SA320CN Double Battery Powered smoke detector. It comes with a 10 year warranty. The First Alert operates with AA batteries and should be checked twice a year for battery life. Both Ionized and Photo Electric smoke sensorsDetects smoke from both smoldering and flaming firesLoud alarm to rapid responseSensors that detect non fires to reduce false alarms10 Year limited warranty– Anthony Dawson View on Amazon See also onAmazon. co. caBest Overall Smoke Detector First Alert SA320CN Dual Sensor 4. 9/5 Product RatingThe Kidde KN COSM B Battery Operated Combination Monoxide detector is a combination smoke and carbon monoxide detector. Carbon monoxide is an odorless and tasteless gas that can kill residents even when low amounts are inhaled. Instead of having both a carbon monoxide detector and a smoke detector, this unit combines the two into one unit.