Automotive Applications Boiler/FurnaceCombustion EfficiencyEngine Testing Boiler/Furnace Measurement Brand Model Oxygen in Combustion Gas Novatech Controls 1732 O2 Transmitter Combustion Efficiency Measurement Brand Model O2, CO Servomex Servoflex 5200 Engine Testing Measurement Brand Model Relative Humidity (%RH) Michell Instruments Optidew