The relative humidity should be maintained between 40% and 60%. Then the best feeling and that feeling says that the humidity in the room perfect.  
The digital thermometer and hygrometer TROTEC H-05 can measure themselves teemperaturu and humidity. The device also has a built-in clock function.

If you are searching for humidity control for automatic control of your humidifier or air dryer, then you can adjust the humidity in the room by using the humidistat Boneco 7056th

Dimensions: 108x60x15 mm 
Weight: 74g (including battery)

Temperature:
Measuring range: 0 ° C to 50 ° C (32 ° F to 120 ° F) 
Accuracy: ± 1.0 ° C (1.8 ° F) 
Resolution: 0,1 ° C (0.1 ° C)

Rel. humidity:
Measuring range: 10% - 90% relative humidity RH 
Accuracy: ± 5% (40% - 80% relative humidity RH) or up to ± 8% in maximum measurements

Battery: 1.5V AAA (included)