Sealed 10-year lithium battery power supply lasts for the entire life of the alarm. 2-in-1 smoke and CO detector with dual photoelectric and electrochemical sensors. A single button to test the alarm and temporarily silence nuisance alarms. Easy to install onto any wall or ceiling without an electrician. Meets the UL 217, UL 2034 (US) and EN 14604, EN 50291 (EU) safety standards. To know more visit: https://www.x-sense.com/collections/combination-smoke-and-carbon-monoxide-alarms