The EE181 is a rugged, accurate air temperature and relative humidity (RH) probe that is ideal for long-term, unattended applications. It includes a proprietary coating on the RH element that increases the life of the element and protects it from dirt, dust, salt, or other contaminants. A 1000 Ω PRT measures air temperature for the -40° to +60°C range. For optimum results, the EE181 should be recalibrated annually.