This Carbon Monoxide Detector features electrochemical sensing technology and photoelectric smoke sensor optimized to detect larger smoke particles produced by smoldering fires, with an LCD display that shows real-time CO concentration & battery life. The alarm is easy to install with a loud 80dB alarm that sounds when CO and smoke levels rise. Battery powered for convenience. Test button to confirm normal operation. Features 1. Carbon Monoxide Detector: Features electrochemical Carbon Monoxide sensing technology and photoelectric smoke sensor optimized to detect larger smoke particles produced by smoldering fires; helps minimize the number of false alarms. 2. Test button: press it for a few seconds to give an audible alarm indicating that the alarm is normal. 3. LCD Display: Clearly indicates real-time carbon monoxide concentration in the surrounding air as well as the remaining battery life, and working status of the alarm. 4. Easy Install and Use: The alarm can easily install with mounting bracket. No hardwired anymore, very convenient to install at home or bedroom-wall. 5. A loud 80-decibel alarm sounds when Carbon Monoxide, and Smoke levels begin to rise. Power supply: 3 AA batteries (Not Included Battery). Specification Material: ABS Color: White Size: 11 x 11 x 4 cm Weight: 100 g, 200 g Battery: 3 AA Batteries(Not Include) Working temperature: -20 C ~ +50 C Alarm decibel 80dB Package Include: 1 Carbon Detector or 2 Carbon Detectors