Combined Gas & CO Detector: Connect this device to a home outlet, then it can continuously adjust the level of carbon monoxide (CO) and flammable gases such as natural gas, liquefied gas (LPG), methane (CH4), ethane(C2H6), propane (C3H8), butane (C4H10), etc. guard. High performance and long service life: This device uses the principle of electrochemical reaction and electrical resistance change of semiconductors to detect carbon monoxide and fire gases quickly and accurately. The sensors of this device have high performance and a long service life of about 5 years. Almost real-time detection: Compared to conventional CO and gas detectors, this device can detect carbon monoxide and fire gas much more often and faster, because the sensors in this device work every 2 seconds. As soon as this device detects fire gas or carbon monoxide with a concentration of more than 50 ppm, it immediately emits a loud acoustic alarm. Multifunctional: This device is also equipped with temperature and humidity sensors. It can accurately measure the temperature and humidity and display the corresponding measurements on the screen. Built-in rechargeable lithium battery: This device has a built-in rechargeable lithium battery with 1000 mAh as an emergency power supply. If the device is connected to an outlet and there is a sudden power outage, the device automatically switches to the power supply due to the built-in battery. The built-in battery can keep the device working for about 18 hours after full charge.