Control systems humidity/t° Prostat PHT-771 Digital Psychrometer Temperature –20–50°C Humidity 0–100% RH 61-100-6013 Eurostat Prostat PHT-771 digital psychrometer: temperature –20°C to +50°C (±1°C), humidity 0–100% RH, 2 AAA batteries / 80h, Hold and °F/°C functions. For EPA and cleanroom monitoring.