With the HSM LED it’s possible to install an optical monitoring of the ionization system at a well observable point.
The high voltage monitor HSM LED can be inserted at any point in the high-voltage wiring between the power brick and the ionizing unit.
The appropriate, "click-zag" supports a wall mounting. The green indicator light flashes when the properly high voltage is supplied. For undervoltage or the lack of high-voltage, the indicator light goes out.