The UV Disk is placed on, or attached to a surface in such a way that the UV sensor on the back of the device is facing the UV lamp to be tested. It records theUV that comes in contact with the sensor, and integrates the data during the irradiation period. The total irradiation level (UV dosage) is subsequently displayed in mJ/cm². With regular measurement, the correct time to replace ageing UV lamps can be determined.