If it is an item that is charged like a phone, tablet, laptop, etc. the chargers and AC adapters convert voltage. If it is a direct plug-in appliance a voltage converter is required unless it is dual voltage and is set to 220v. I tried explaining this to my wife on our first trip to the UK but she felt the plug adapter was sufficient. When her curling iron went "snap, crackle and pop" my problem what to buy for her next birthday was solved.