First alert, 2 pack, dc, battery operated, carbon monoxide & smoke detector combo pack, utilize ionization smoke sensing technology that's ideal in identifying flaming fires, a mute button has been included to serve the dual purpose of silencing nuisance alarms & testing the functionality of your alarm, featuring an increased nod to safety with an 85 decibel sound output, 10 year limited warranty, note: please check your local building code requirements before installing this product to determine compliance with applicable standards.