For those of you with mk3 straighteners who are going to USA (like me!!) and are worried they won't work - I emailed ghd who confirmed they won't work due to voltage but new mk 4 ones will. If you are users of ebay you will find there is a thriving market for used mk 3 ghds - I have just sold my mk 3 pair for £70 - a good amount towards my new mk4 pair which I got for £109!