According to the European standard "ball" of the tow bar has a single size. The “iron” of the tow bar itself can be complete, and it can be collapsible (with a detachable ball). Folding looks beautiful when you do not need a hitch, but it costs significantly more expensive.
Outlets there are two types:
1. 7 gangue. Allows you to connect only sources of external lighting of the trailer. Suitable if you have a regular cargo trailer.
2. 13 gangue. This outlet was just designed to connect the trailer dacha and maintenance workers all of its devices. In addition to sources of external lighting, this outlet has separate outputs for connecting the refrigerator and recharging the battery in the trailer (for this, a separate wire is pulled, which runs from the car battery to the outlet through its fuse). Such an outlet is more expensive compared to 7-wire and its correct connection is more laborious. The following is the pinout of the sockets 7 and 13 wires:
If it so happens that the outlet 7 on your car is vein, and on the trailer 13 is vein or vice versa, it does not matter. For this case, there are convenient adapters 7/13 or 13/7, which you can purchase in our store Retrailer.