The Tive trackers measure the relative humidity (RH) which is the amount of moisture in the air compared to what the air can "hold" at that temperature. The devices use a digital humidity sensor which operates with a similar principle as the wet- and dry-bulb hygrometer. A relative humidity measurement of 100% means that the air is holding as much moisture as it can at a given temperature, in the form of water vapor.
The devices can measure relative humidity with a typical accuracy of ±2 %RH and a maximum tolerance of ±4.5 %RH between the range of 10 to 90% RH. The typical accuracy increases to ±4 %RH when relative humidity is above 90% RH and below 10% RH. Below is a diagram showing the maximal and typical tolerance of RH @ 25°C.
The resolution of the humidity measurement is 0.1 % RH