Some CO2 sensors are too simple. Other CO2 analyzers are costly and complex. But the LI-830 and LI-850 are just right – bringing proven performance at an economical price to provide CO2 gas measurements that you can depend on day after day. The LI-830 measures CO2 in air. The LI-850 measures both CO2 and water vapor in air. The H2O measurement allows the LI-850 to account for band-broadening due to water vapor, and therefore the LI-850 reports CO2 concentrations with precision of 1.5% of the reading, in contrast to the 3% precision provided by the LI-830.