The testo 310 has two measurement cells for O2 and CO, and a temperature sensor integrated into the flue gas probe. The gas sensors measure the exact oxygen and carbon monoxide content as well as the flue gas and ambient temperature. From these data, all relevant measurement parameters such as CO2 value, degree of effectively and flue gas loss are calculated. The instrument stands out thanks to its easy handling and simple menu structure. You can read off the measurement values confidently and conveniently from the well-lit display, even in bad light conditions. The fuels are stored not just as numbers, but are each described. At the top edge of the clear display, the symbols for the different measurement menus are always in view. The display and the dirt-insensitive keypad are clearly structured. Operation is very easy – even if you only have one hand free.