?Upgrade Plug-in Combination Gas Carbon Monoxide Detector? Plug and play, easy to install, 4-in-1 sensor, real-time monitoring display and alarm. ?Combination Gas Carbon Monoxide Sensor? Adopting catalytic combustion sensor and electrochemical sensor, real-time monitoring the concentration of combustible gas and carbon monoxide, with sharper and more accurate sense of smell. ?Temperature?F? and Humidity Sensor?Real-time detection and display of temperature and humidity, let you know the environment in real time. ?85dB Alarm Sound?Combination gas and carbon monoxide detector will alert you immediately when the combustible gas or carbon monoxide concentration reaches the default value. ?Upgraded Design Round Color Screen?Color display with bigger and clearer digital display. ?Application?Combination gas and carbon monoxide detector is suitable for home, restaurant, apartment, office, hotel, petroleum plant, gas station, campervan, etc.