Most phone and computer chargers will accept both 120 and 240, and convert it automatically (acceptable voltages are printed in very small script on each box), so all you need is a cheap adapter that adapts the prongs so they fit French outlets. Things like curling iron, hair dryer, etc cannot convert 240 to 120, and for those you need to have a converter box. Carol's advice is good, to inquire to see if they already have a converter box available.