The Grozone HTC Climate Controller can be used to control relative humidity, temperature, and CO2.
It has 2 outputs, a 4-digit digital display, and can be set to use for day, night or 24hrs.
Humidity is displayed from 0-100% and the relative humidity is controlled from 0°C - 100°C. There are different setpoints as well as a 24 hr data log for each sensor.