At the trailer hitch the trailer is connected to the vehicle and in the worst case damage can cause the trailer to detach from the vehicle. A cover for the trailer hitch protects this part and ensures a long service life. A trailer hitch cover is not mandatory, but it is useful and an expense that is really worth it.
The simplest covers are small softballs in red and black color. A protective cover with a bar mount is very inexpensive. If you want to spend a little more money, go for the Lubrifix cover cap, which has a lubricator in the ball coupling that greases the coupling at the same time.