Temtop Smart Air Quality Monitor Indoor Air Quality Meter with PM2.5, AQI, Temperature, and Humidity Detector for Home, Office, or School, App Connectivity, 60 Day Battery Life Singlets 【HIGHLY ABSORBENT】These activated carbon filters B0CKMZKR78 【HIGHLY ABSORBENT】These activated carbon filters (fibrous) are made of high quality powdered activated carbon as the adsorption material and use the knob on the back side to adjust to fit your head size Precision and Reliability With over 10 years of experience in laser sensor R&D of laser sensors and combined with Sensirion digital Temperature and Humidity sensors Subversive Innovation This Air Quality Monitor not only detects Temperature and Humidity but also monitors air quality