It is an voltage protection which prtects and extends the service-lifeof connected electrical equipment (TV,Fridge,Computer, etc.)safe. 

When voltage is higher or lower than normal voltage, it  cut off to protect the equipment  safe.    

We can set the hither and lower voltage according to our normal voltage.            

 Green lamp means voltage is normal, when green lamp is cut off and red lamp works it means the voltage is higher or lower

low  voltage:180v   high  voltage:260v 

13AMPS   3500W