Ideal for monitoring indoor air quality in homes, offices classrooms, hotels or anywhere air quality is important., and is especially helpful in preventing the spread of Covid-19. Provides audible alarms for CO2 threshold. Maintenance free NDIR (non-dispersive infrared) sensor using waveguide CO2 technology, ensures long-term accuracy, stability and reliability. The compact design features a large display with a bar graph indicating CO2 trend for up to 24 hours. 3 backlight colors indicate air quality status with four additional user selectable backlight color choices. Calibrates easily to fresh air and comes with a USB power cable. Will stand on a desktop or can be wall mounted.