The FireAngel alarm uses enhancing sensing to detect carbon monoxide quickly. It spots rising CO levels early and prompts you to ventilate in time. And if the alarm goes off while you are out, the memory function keep track, so you will know what happened. The loud 85 dB alarm makes sure everyone at home hears it straight away. Good to know - With Sleep Easy mode, low-battery warnings are limited overnight - Smart Silence helps stop false alarms without fully switching it off - The large test button makes it easy to check or hush the alarm - The sealed battery lasts up to 10 years, so you won't replace the alarm often