The Extech CO100 is a CO2 desktop monitor for indoor air quality that measures carbon dioxide (CO₂) concentrations from 0 to 9,999 ppm, air temperature from -5 °C to 50 °C (23 °F to 122 °F) and humidity from 0.1 to 90 % relative humidity. The measuring device has a call-up function for the maximum/minimum CO₂ value. The scope of delivery includes a maintenance-free NDIR CO2 sensor (NDIR = non-dispersive infrared) and a universal power supply unit for alternating current.