This is an automatic Voltage Transformer with built-in voltage regulator. Converts 110/120 V to 220/240 V OR converts 220/240 V to 110/120 V (switch is on back of unit)Compatible with 50Hz/60Hz.This stabilizer can regulate big range fluctuating voltage into general voltage output.Input Voltage AC 75V-130V or 180V-260V.Output Voltage: AC 110V+-4% or AC220V+-4%.On/Off switch with indicator lamp Analog meter on front of unit shows exact output voltage Voltage stabilizer good for countries with unstable voltage supply 3 outlets on front of unit (outlets accept 3 or 2 prong US plugs and 2 prong Euro/Asian plugs). One of the outlet is a Universal outlet that can accept plugs from most foreign countries. NOTE: Leave at least a 100% slack for the transformer. TVs, Heating appliances, Laser printers and Power tools spike when you turn them on. For these products you need to buy a transformer that is at least 3 times the items capacity