OM-CP-PRHTEMP101A is a low cost, state-of-the art pressure, relative humidity and temperature data logger for use in museum and archive preservation, shipping and transportation, warehouse monitoring, HVAC, clean rooms, clinical laboratories and altitude validation and studies. Using the software, starting, stopping and downloading from the OM-CP-PRHTEMP101A is simple and easy. Graphical, tabular and summary data is provided for analysis and data can be viewed in °C, °F, °R, K, for the temperature channel, %RH, mg/mL and dew point for the humidity channel, and mbar, PSI, inHg, mmHg, atm, Torr, Pa, m, kPa, MPa for the pressure channel. The OM-CP-PRHTEMP101A is a major leap forward in both size and performance, Its real-time clock ensures that all data is time and date stamped. The storage medium is non-volatile memory, providing maximum data security even if the battery becomes discharged.