Features:  Air Quality Monitor: Carbon dioxide tester can detect carbon dioxide concentration in the air, it can be widely used in home, classroom, hotel room, apartment, office, gym, etc.  2 Types Optional: Type 1 features time display and 3-color screen display (Green, 400-1000PPM; Yellow, 1000-3000PPM; Red, 3000-5000PPM). Type 2 has mirror surface and more accurate readings.  Accurate Sensor: Adopts NDIR/ semiconductor detection principle, air convection detection, quickly and accurately detects CO2 in the living environment.  Alarm Buzzer: When the CO2 concentration is above 1000PPM, the buzzer will beep to remind of you, long press the power button to stop it.  LCD Screen: Displays carbon dioxide, battery level, temperature and humidity. With large LCD screen, clear to read even in dark environment. With stable base, easy to be placed on the desktop.  Rechargeable Design: Built-in 1000mAh rechargeable lithium battery for long using time, comes with USB cable, quick to charge it via power adapter, power bank, laptop, etc.    Note:  1. Please read the user manual carefully before use.  2. Size and color may be slightly different due to manual measurement and different lighting conditions. Thanks for understanding.    Specifications:  Type: Type 1/ Type 2 (Optional)  Color: White  Material: Plastic  Screen: LCD Display  Input: 5V 1A  Temperature Measurement: Range 0~60℃, Resolution 1℃  Humidity Measurement: Range 10%~99%, Resolution 1%  Detection Principle: NDIR/ Semiconductor  Carbon Dioxide Testing: Range 400-5000PPM, Resolution 3PPM  Alarm Buzzer: Support  Screen Display of Type 1: Green (400-1000PPM), Yellow (1000-3000PPM), Red (3000-5000PPM)  Working Environment: Temperature 0℃~60℃, Humidity ＜98%  Built-in Battery: 1000mAh Lithium Battery  Item Size: 82 * 82 * 52mm / 3.23 * 3.23 * 2.05in  Item Weight: 104g / 3.66oz (Type 1); 107g / 3.78oz (Type 2)  Package Size: 11 * 11 * 6cm / 4.33 * 4.33 * 2.36in  Package Weight: 148g / 5.21oz (Type 1); 161g / 5.68oz (Type 2)    Package List:  1 * Carbon Dioxide Tester  1 * USB Cable  1 * User Manual (English)