UNI T Air Quality Meter A25D is a meter used to measure PM2.5 concentration. A-25D air pollution meter, PM2.5 concentrations are used to display different emoticons on-screen to help users visualize their environmental conditions. This best indoor air quality meter has a large 3.0 LCD screen, a clear digital readout. Operating button, is easy to control. The A 25 D air pollution check meter can be used in homes, laboratories, offices, hotels, schools, factories, conference rooms, airports, hospitals, restaurants, and many other public places. Features: Precise PM2.5 concentration based on pre-calibrated sensors Temperature measurement (℃/℉) Humidity measurement Emoticon display LCD backlight and red backlight alarm Battery status, low power, auto power-off Specifications: PM2.5 (ug/m3): 0~100, 101~400, 401~500 PM2.5 (ug/m3) accuracy: ±(10ug/m3+10dgts), ±(10%+30dgts), ±(10%+50dgts) Temperature℃: -10~50℃ Temperature℃ accuracy: ±1℃ Temperature℉: 14～122℉ Temperature℉ accuracy: ±1.8℉ Humidity: 5%~99%RH Humidity accuracy: ±5%RH@30%~80%RH, ±8%RH@<30%RH, >80%RH Auto power off: Yes Low battery indication: Yes Red backlight alarm: Yes LCD backlight: Yes Concentration emoticon: Yes Power: 1500mAh rechargeable polymer battery LCD size: 3 inches Product color: White and grey Product net weight: 250g Product size: 30mm×20mm×50mm Standard accessories: 1.5m mini USB interface cable Package Includes: 1 x UNI T PM2.5 A25D Air Quality Temperature and Humidity Meter