Easy for installation, wall mounted High quality, good reliability and stability. Testing and reset button, low voltage warning. Clear LCD display, up to 85 dB alarm loud sound. The Elector chemistry carbon monoxide sensor, makes it accurate. Permanent carbon monoxide sensor The alarm sound pattern is four short alarm beeps. The red LCD will flash while in the alarm mode. One chirp every 30 seconds in an indication that the battery is low (need replacement) (green LCD still flashes once every 30 seconds). Test/Reset button to test the unit electronics and verifies proper unit operation and reset the unit during CO alarm. Alarm memory feature: If the unit ever alarms, pressing the button, green LCD will flashes once every second for one minute and the peak alarm level will be indicated on the LCD. Green and red LCD lights that indicate normal operation and alarm status. The unit will sound chirp and red LCD flashes once as power up. Operating voltage: 5 (V) Alarm current: 20 (mA) Working temperature: 5-40 Detection range: 20 (m) Scope of application: household / commercial type gas alarm detector Installation: Ceiling Weight: 120 (g) Alarm: live alarm Power: 3 x AA batteries 1.5V Alarm current: 75mA Frequency: 3KHz Working humidity: 20-90%R.H. Diameter: 100mm High: 38mm Sensitivity &Time :50ppm. Alarms within 60-90 minutes 100ppm. Alarms within 10-40 minutes 300ppm. Alarms within 3 minutes Standby Current<50uA (without LCD); <200uA (with LCD) 1 x Carbon Monoxide Alarm 2 x Set of Screw 1 x User Manual Due to the difference between different monitors, the pictures may not reflect the actual color of the item. Compare the detail sizes with yours, please allow 1-3cm error, due to manual measurement. Please leaving a message before you give the bad feedback, if the products have some problems. Thanks for your understandings.