The carbon monoxide detector constantly monitors carbon monoxide levels to keep your family safe. Powered by 2*1.5v AAA battery (not included), portable and easy to install, no plug needed, not affected by power failure, can be installed anywhere! Features With an advanced electrochemical carbon monoxide sensor, it accurately detects carbon monoxide levels no matter where the detector is placed in the room. To ensure complete protection, be sure to place one on every floor and in every bedroom of your home. Simple to use, just one button test/reset and when levels dangerous carbon monoxide are detected, the red LED flashes with a loud alert mode - the led flash emits an alarm of 85 decibels. Alarm standard: 50ppm, alarm within 60-90 minutes; 100 ppm, alarm within 10-40 minutes; 300ppm, alarm within 3 minutes. Note: When testing the detector, please do not use gas to blow directly into the hole. All Co alarms are rigorously tested and UL listed. We promise and guarantee to respond to all questions, concerns and inquiries within 24 hours, providing service to our customers.