battery charger 120-220 50-60Hz for laptop, telephone etc

[J4e8a16n]

Hi,

Battery charger 120-220,   50-60Hz  from Samsung, Toshiba, etc.,    for laptop, telephone, etc.  How true, good are they?
Is there tutorials on this subject?
What would be a good 220-120 volts adapter for voyagers.


For example:  http://www.amazon.ca/Goldsource%C2%AE-STU-200-Voltage-Transformer-Converter/dp/B0022TMB9A/ref=pd_cp_23_2?ie=UTF8&refRID=09HBZEQCJ7QVF620GC16

Thanks for your attention,

JPD