The ITUS-4 device is intended for monitoring the state of non-linear surge arresters. The "ITUS-4 Client" application allows to work with the ITUS-4 device through the NFC interface built into the smartphone. Using the "ITUS-4 Client" application, you can: • Read all the data from the ITUS-4 necessary for assessing the performance of the surge arrester. • Record in the internal memory of “ITUS-4” data on the object on which the device is installed, with the further possibility of changing these data. • Read information on leakage currents and the number of pulses transmitted through the surge arrester. • Save read data to the phone. • Generate a report on saved data from all ITUS-4 devices surveyed.