【How to Use Carbon Monoxide Detector】 Powered by AA batteries, it will automatically turn on after charging, then enter working mode (the screen will turn off immediately, which is normal). When the concentration is higher than 30 ppm, the screen will light up and display the value for you to check at any time. 【Carbon Monoxide Detector】 Equipped with an LCD screen for easy reading of real-time values (ppm), it has audible and visual alarms. When the concentration exceeds a certain threshold, an audible alarm and a red light will flash. This allows you to quickly and clearly know the ppm concentration and take appropriate measures to effectively protect your people and property. 【Alarm Self-Test】 To test the product's effectiveness, perform a self-test by briefly pressing the button. If the value is not displayed on the screen and an orange light is on, it indicates that the battery is fully charged and reminds you to replace it quickly. 【Widely Used Carbon Monoxide Detector】 Equipped