Enerac M700 Combustion Analyzer is a complete stack and exhaust gas analysis system in the palm of your hand. Enerac M700 Combustion Analyzer measures O2 (0-25%), CO SEM Sensor Dual Range (0-500/2,000 or 0-2,500/10,000ppm), Draft, Combustibles (0-6%), (Dual ranges for CO, SO2 , NO & NO2; (not available if Combustible Sensor is selected) Stack & Ambient Temperature. Free ground shipping within continental US. All of the Enerac combustion and emission analyzers are made in the USA. Please contact us to select probes and additional sensors.