We have many types of stabilizer, The photo is only one of them.
SVC fully automatic voltage regulator consists of contact voltage regulator, Sampling control circuit and servomotor as well . 
SVC-E digital display fully automatic AC voltage stabilizerApplicationSVC fully automatic voltage regulator consists of contact voltage regulator,sampling control circuit and servomotor as  well .It has excellent features,such as small waveform distortion,high efficiency,high power factor,free from the effect of frequency variation of supply .It can be wid ely used in most situations where the voltage stabilization are required.SpecificationInput voltage      Single-phase 150V-250V     Ambient temperature    -10 -40Output voltage  Single-phase 220V or 110V  Relative humidity        <95%Stabilizationaccuracy       220V 3%or110V 5%    Temperature rise       Lower than 60Frequency       50Hz or 60Hz           Waveform distortion  No additional  waveform distortionDebug time     <1s(input voltage                                 0.8 variation of 10%)Efficiency       >90%                    Dielectric strength       1500V/minVoltageregulating      245V 4V                  Insulation              >2MDelay time     Within 0.5s against10%              input voltage deviation      Overload power factorPacking informationSpecification(VA)    Dimensions(CM)     Weight(KG)   Packing size (CM)