Range: Relative humidity, 0 to 100%; Temperature, -4°F to 158°F (-20°C to 70°C); Dew point, -40°F to 176°F (-40°C to 80°C); GPP, 0.55 GPP to 3,868 GPP. Resolution: Relative humidity, 0.1%; Temperature, 0.1°. Accuracy: Relative humidity, ±3%; Temperature, ±1.8°F (1°C). Power: one 9V alkaline battery. Battery life: approximately 55 hours of constant use (no backlight) or 23 hours (with backlight).