CO2 Gas Sensor (For LabQuest, LabPro, Go! Link, and CBL 2)...The CO2 Gas Sensor measures gaseous carbon dioxide levels in the range of 0 to 100,000 ppm. It has two settings: low range (0 - 10,000 ppm) and high range (0 - 100,000 ppm). This probe is great for measuring changes in CO2 levels during plant photosynthesis and respiration. With this sensor, you can easily monitor changes in CO2 levels occurring in respiration of organisms from crickets to humans! The CO2 Gas Sensor is easily calibrated using a calibration button. A chamber with probe attachment is included for running controlled experiments with small plants and animals.