TPI 717 Combustion Analyzer with Replaceable Sensors is designed to measure CO, O2, and flue temperature in addition to calculating excess air, efficiency, CO2 & CO/CO2 ratio. The TPI 717 features a long lasting 10,000 ppm CO sensor, in-line water trap to prevent the sensor from water damage, in-line pump filter to prevent the pump from becoming clogged, multiple fuel compatibility, self-diagnostics, and more. The TPI 717 is a great combustion analyzer with many convenient extra features like a built-in differential manometer and differential thermometer.