Formaldehyde Tester Carbon Monoxide Measurement Range (PPM) Not Applicable Carbon Dioxide Concentration Not Applicable Temp Range Not Applicable Relative Humidity Range Not Applicable Dew Point Range Not Applicable Oxygen Concentration Not Applicable Accuracy +/-5 Percent Resolution 0.01 mg/m (ppm) Display Backlit Dual LCD Auto Power Off Yes Power Source Rechargeable Li-Ion Battery