DESC: SCO403 included 1 - CO400 battery operated carbon monoxide alarm and 1- SA303 battery operated smoke alarm CO detector is a modern, compact design with no installation required with electrochemical sensor - the most accurate technology available while the smoke alarm uses ionization smoke sensing technology Simple to use silence/test button; low battery warning; end-of-life timer; Loud 85 decibel alarm Convenient front battery access for easy replacement with (2) AA batteries included for the CO and (1) 9-Volt for the smoke alarm 5-Year limited warranty, Manufacturer: First Alert