ENC cannot be transferred from one category to another. Therefore, when making a purchase, think carefully about which vehicle category you need the ENC device for. Example: if you make one trip in a passenger car with a trailer, you will need a category II. device. If you will go back without the trailer, you need a category I. device.
The sale of the device is not linked to the vehicle plate number. You can freely share your ENC device with your friends and family. However, it is important to keep to the category, for which the ENC was purchased.
These accessories do not count towards the overall height of the car. So if you have a roof box or a roof rack on the roof of your car, you will still need an ENC device for category I.