Many years I was carrying a lot of adapters with me meanwhile traveling and now I found the perfect solution.  These two world adapters from Skross. One just for USB (two entrances) and the other one for plugs. They fit in every country and is all I need. Just perfect 🙂

Price from 19€ and to find for example at Amazon or at Media Markt or at almost any duty-free shop of the airport and airplanes.