Universal Security Instruments 4-in-1 Universal Smoke-Sensing Technology Hardwired Smart Alarm, Model MDSCN111 4-in-1 Smart Alarm protects against fast-flaming fires, smoldering smoke, carbon monoxide and natural gas (or methane) Features a quick activation pull-tab and a front-loading battery drawer for replacement without removing the alarm from the bracket Designed with aback-up battery Suitable for houses, apartments, and mobile homes Comes with a seven-year limited warranty