Features: PERFECT DESIGN --- 3.93x3.93x1.5 inches, Portable and easy installation.the Cqlunuoly carbon monoxide alarm instantly and accurately detects CO, an invisible, deadly gas, giving you the earliest possible warning of CO threat with both a loud 85 dB alarm and a rapid flashing red LED. ALARM WARNING --- When a Dangerous level of Carbon Monoxide is detected, the Red LED will flash and a loud alarm pattern will sound, Loud 85 decibel alarm with LED Flash While in the Alarm Mode for the Life-Saving Safety. SAFETY AND VISIBLE --- Protect Our Family from CO, With 3 digits of LCD Displayer is Optional, 'Err' indicates the unit malfunctioning. 'Lb' indicates its low battery and needs to replace '999ppm' indicates CO level over 999ppm. 'actual concentration' when less than 999pm. ENERGY SAVING --- Operated by three 1.5V AA Batteries (not included), The alarm sound pattern is 4 beeps every 5seconds for the first 4 minutes. In 4 minutes, it will change to 4 beeps every minute to save the battery. ALARM STANDARD --- 50ppm, alert within 60 to 90 minutes; 100pm, alert within 10 to 40 minutes; 300pm, alert within 3 minutes. Note: When you test the detector, please do not use gas to blow the hole directly. Test the alarm First, HOW TO TEST IT: Step 1: Install the batteries in clean air , then press the test button for five seconds to test the units electronics, beeps will sound if it's normal; Step 2: Leave it in clean air for one minute; Step 3: Then put it into a sealed bag, spray some CO gas into the bag and seal it. Waiting for about one minute, the Alarm will go off if it's normal. UNIQUE DESIGN — Portable and easy installation. Turn the alarm body counterclockwise and take off the bracket. Hold the bracket in the installation position as specified in the Recommended Locations,mark installation holes of the bracket with pencil. Drill the two marked installation holes.Tap the two plastic gromments into holes with hammer. Mount the bracket to the ceiling by inserting and tightening the supplied screws into plastic grommets. Fix the alarm on the bracket and turn the alarm body clockwise , until fully inserted on the bracket. Applicable Place The alarms Suitable for all the Place Possible to Produce Carbon Monoxide , Such as your Home Kitchen, Bedroom, Bathroom, Hotel. Also Useful When you are Enjoying the Barbecue, Using Charcoal Warm yourself, or Putting it in your Parking Garage, etc. Advanced electrochemical CO sensor The advanced electrochemical CO sensor detects carbon monoxide leaks from multiple sources, such as faulty fuel-burning appliances, blocked chimneys, and generators running inside or too close to homes. Unique alarm sounds and indicator lights on the face of the detector distinguish a warning from a carbon monoxide warning. Battery Operated for Convenience The battery-operated CO alarm installs in minutes, without requiring an electrician. The unit requires 3 AA batteries and features a chirp and indicator light to let you know when they need replacing. Package Includes: 2 x Alarm 4 x Screws 1 x User Manual