Testo 300632 3153 315 3 co and co2 meter for ambient measurements testo 300632 3153 p cutting edge technology easy to use rugged design these are just a few of the features which make the testo 315 3 stand out head and shoulders above the rest the co and co2 meter is designed to measure carbon monoxide and carbon dioxide in parallel in ambient room conditions the readings are presented on an easy to read display p p a visual and an audible alarm are activated when co co2 thresholds