The Edgetech PDM75-X3 Hygrometer features drift-free accuracy, NIST traceability, low maintenance, high durability and ease of use in a portable package, resulting in a system ideally suited for the demands of field use. The Model PDM75-X3 has all the standard features Edgetech Instruments DewMaster Hygrometer in a portable package, with a modular chilled mirror sensor that is chemically resistant to background gases, configured to meet your dew/frost point measurement requirements.