Hello Remy, it isn't, I bought mine in Hawaï and I tried it in french polynesia and then in Samoa, the difference between these country was enormous :
Great control at 2,8km from the controller without any problem when I flew in Samoa and at about 1,3km in french polynesia I'm loosing control....
On my box it's us version and I clearly saw the difference of power when changing you're changing countries.