Tramex 4.5" Relative Humidity probe for TREMS Xtra - RHP-SWThe Tramex 4. 5" Relative Humidity Probe for TREMS Xtra (RHP SW) is a high precision sensor designed for use with the TREM Xtra Remote Environmental Monitoring System. This reusable RH probe provides accurate, real time measurement of in situ Relative Humidity, Temperature, Dew Point temperature, and grains per pound humidity ratio. It is ideal for assessing wall and cavity structures as well as ambient air conditions within the building envelope.