Airstreams originally are equipped with electric brakes that are controlled by a brake controller in the car. That is the standard in most of the world. Brake controllers can be purchased in the supermarket for a few dollars.
In Europe, a vehicle must be able to brake autonomously.That is why a special brake controller has been developed that is placed in the trailer. The EU brake controller is available for both electric brakes and electric hydraulic brakes (5th wheels). Because of the very limited editions and because of the technique, the EU controllers are many times more expensive.
American Airstreams can be provided with the EU controller or the shaft must be converted to the backstop.Both systems require the same investment