For both reptiles that need things dry and especially for reptiles that need a humid environment, a Komodo Analogue Habitat Hygrometer is an essential piece of kit for allowing you an accurate reading of the humidity levels in your terrarium or vivarium.
 
Especially for rainforest reptiles, humidity is incredibly important, helping them keep healthy skin and scales and effecting the way they respire, and while there are plenty of ways to increase humidity levels, the only accurate way to monitor them is with a hygrometer like this Komodo Analogue Habitat Hygrometer.
 
Keeping one inside your terrarium allows you to keep a close eye on humidity levels, and take swift action should humidity fall outside of the optimum parameters for your reptile.