1. Professional CO2 Monitor -- Versatile carbon dioxide detector can detect CO2, temperature and humidity. 2. Audio and Visual Alarm -- As the CO2 concentration is over setting value the CO2 tester will ring and change ligh to reminding you. 3. 2.8inch True Color Screen -- Large clear FPC true-color display screen simultaneously display CO2 concentration, temperature and humidity, date and time. Special designed with 6 colorful section to indicator the CO2 concentration range, easy to know the air qaulity just for a glance. 4. Data Logger -- Customizable recording start and finish time, also include recording interval (hour-minute-seconds). Built-in storage for continuous data logging, you can track trend data up 80000 groups data for co2 concentrations, temperature, humidity. 5. USB Rechargeable --- This model now has a rechargeable 1500mAh battery. You can press "LIGHT" button to turn off the monitoring and it will keep testing, and can carry on 24 hours uninterrupted monitoring to air quality if you into adapter to charge it. It will always take care of your breathing.