The testo 810 is a handy temperature measuring instrument which measures air temperature, and simultaneously surface temperature by infrared. For example, the temperature of a radiator, an air outlet or a window can be easily and conveniently compared to the air temperature in the room. The difference between air and surface temperature is automatically displayed. Thanks to its handy design, the testo 810 is quickly to hand and easy to stow, for example in a trouser pocket. The infrared measurement is carried out with a 1-point lasermeasurement spot marking and 6:1 optics. The emissivity can be individually set depending on the application, and with the help of the min./max. function, the minimum and maximum values are shown in the display.