The Extech RHT50 records Relative Humidity (0 to 100%RH), Temperature (-40 to 158°F /-40 to 70°C) and Atmospheric Pressure (13.7 to 15psi / 950 to 1050hPa / 95 to 105kPa / 0.9 to 1.0bar). Logs up to 10,000 readings with user programmable sample rate from 1 minute to 18 hours. USB interface for easy set-up and data download. Selectable Atmospheric Pressure Units: psi, hPa, kPa, and bar. User-programmable High/Low alarm thresholds. Manual and Programmable start modes. Status Indication via Red/Yellow LED and Green LED.