KNOW AT A GLANCE: Large and clear reading, with 3-color indicator lights, know the air quality immediately from wherever you look at it. | 4-IN-1 MULTI-FUNCTION: Measure PM2.5, AQI, TVOC, and HCHO, with sensitive Temtop 3rd generation laser particle sensor and Dart electrochemical sensor. | EASY TO USE: A home button realizes all operations, including power, interface switch, and display cycling. The 2200mAh battery provides portable power when USB charging is not available. | CALIBRATION AVAILABLE: The HCHO sensor supports easy calibration. To ensure the accuracy of the sensors, make sure it is placed in a ventilated environment (indoor or outdoor) for at least 6 hours before used for the first time or after stored for a long time. | WHAT YOU GET: M10, Charging Cable, Reset Pin, User Manual, Temtop 12-months Warranty & 24/7 Customer Support Access via Email and Phone.