Mini CO Detector: The electrochemical gas sensor of this CO detector is very sensitive to any CO leaks in your home detector. Mini size: 6.2cm * 2.8cm Use: Prevention of carbon monoxide poisoning - When the CO concentration exceeds the standard, the detector sounds an alarm and the red indicator flashes until the amount of ambient gas temperature drops below the alarm threshold. LED and sound: The LED indicator flashes red and the alarm volume is 85dB to remind you to alert you. all family members that CO has been detected. Sensitivity and alarm duration: The alarm duration depends on the carbon monoxide concentration level: 50 ppm, alarm within 60-90 minutes; 100 ppm, alarm within 10-40 minutes; 300 ppm, alarm within 3 minutes. Package Contents: 1 CO ALARM, 2 screws, 1 English user manual (2 AA batteries not included).