5 In 1 Air Quality Tester CO2 TVOC HCHO Temperature Humidity Test Digital
Clear Indication: This tester features CO2 concentration level indications. It flashes green at 0 to 799ppm, yellow at 800 to 1199ppm, orange at 1200 to 1599ppm, red at 1600 to 1999ppm, and 4 colors flashing at 1999ppm.