The Extech RHT50 records relative humidity (0 % RH to 100% RH), temperature (-40°C to 70°C / -40°F to 158°F), and atmospheric pressure (13.7 psi to 15 psi / 950 hPa to 1050 hPa / 95 kPa to 105 kPa / 0.9 bar to 1.0 bar). It logs up to 10,000 readings with user programmable sample rate from 1 minute to 18 hours. Includes USB interface for easy set-up and data download, user-programmable high/low alarm thresholds, and both manual and programmable start modes. Selectable atmospheric pressure units: psi, hPa, kPa, and bar. Status indication via red/yellow LED and green LED. Complete with 3.6V Lithium battery, mounting bracket, and Windows® compatible analysis software.