AC 80-300V US plug LCD digital voltmeter volt panel meter voltage tester gauge plug type digital voltmeter is widely used in AC 80-300V mains measurement. This instrument directly inserted in the flapper or plugged into a wall switch, and can display the current mains voltage.
The biggest advantage is that when you see the current voltage is too low or too high, you can choose to switch off the running of a household appliances or equipment to protect your home appliances and equipment life. It can also be a simple voltage test table. Great helper in family, office space, industrial and mining enterprises, etc..

Potentiometer adjust: 
Use screwdriver to open the outer case of the voltage meter 
Use screwdriver in small size to adjust the potentiometer 
If display voltage is too high, adjust potentiometer in counter-clockwise 
If display voltage is too low, adjust potentiometer in clockwise 
packing including:
1x US plug LCD digital voltmeter