[2 in 1] This smoke detector and carbon monoxide detector uses a high-sensitivity photoelectric smoke sensor and a high-precision electrochemical CO sensor. The two sensors operate independently in one unit and can detect smoke concentration and CO concentration respectively. 85 dB Alarm: When smoke or carbon monoxide is detected, the alarm sound over 85 dB and the red LED flash. For increased reliability and accuracy, it is recommended to install multiple devices in your home. Suitable places include living rooms, bedrooms, hallways, garages, and basements. LCD Display: The smoke detector carbon monoxide detector combination uses a large LCD screen that displays the CO concentration level in the air in real time, clearly and intuitively, allowing for easy and accurate monitoring throughout the day. Easy to Install: Powered by a 9V battery (not included, need to bring your own), the smoke carbon monoxide detector is easy to install, no additional wiring is required, and can be easily mounted or ceiling - screws and brackets included. Colour:White Material:ABS Package Contents: 4 * Detector Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.