The OptiSonde chilled mirror hygrometer is a humidity transfer standard available in benchtop or wall mounted configurations. The analyzers are connected to either a single or two-stage chilled mirror sensor and PRTD. Chilled mirrors are the humidity sensors commonly used for laboratory and process measurements that require high precision without long-term drift. The instruments have a built-in data logger and display and transmit in a variety of parameters, such as dew point, relative humidity, dry bulb, wet bulb, absolute humidity, volume ratio and mass ratio. Common applications for the instruments can be found in environmental test chambers, engine test cells, clean rooms, air-conditioning and heat exchange coil testing, and metrology labs.