Six test signal frequencies (20Hz, 50Hz, 60Hz, 200Hz, 500Hz and 2kHz) can be selected by pressing the appropriate button on the front panel. Each button has a dual function. For example, pressing the 20Hz button (steady LED indication) selects 20Hz as the test signal frequency. Pressing it again (blinking LED indication) selects 50Hz as the test signal frequency. Frequency is primarily used to enhance the signatures of reactive components such as capacitors and inductors.