Eti 6000 series therma hygrometers eti 224 612 this therma hygrometer from eti has been manufactured to a high standard and is the ideal instrument for measuring relative humidity and air temperature the unit measures rh over the range of 0 to 100 rh with a resolution of 01 rh and temperature over the range of 20 to 70degc with a resolution of 01degc 20 to 50degc with a fixed probe the hygrometer has a host of rich features including a custom lcd displaying rh degc