To measure various climate and processes values with a handheld, user-friendly instrument requires extraordinary measurement technology. The handheld meter of the OMNIPORT 20 series meets these multiple demands. The selection of the appropriate sensing probe and accordingly the configuration of the handheld meter allow for displaying the following values with the highest accuracy: Indicate : relative humidity RH , temperature T,dew point temperature Td, absolute humidity dv, mixing ratio r, air velocity v, water activity (in oil) aw, water content (in oil) ppm