Originally Posted by deniah

Some plug converters have no marking at all.

If they do, they'll have a max voltage and current (eg 250V 10A). They wont list a range. If it fits in a common euro socket it certainly supports euro voltage.

What he actually needs to look at is is the "iPhone charging 'cube'" itself (and those for other devices he intends to use). That's the important bit. And all the ones I've encountered are 100-240v. Meaning they'll work just fine.