First post and all that; been towing trailers and caravans for years but still feel like a newbie sometimes :)
With the above statement in mind, I fear I maybe about to be today year's old when I finally find out what this part of a coupler is for. I am starting to think it is nothing more than somewhere to place the electrical coupler when not in use but really am not sure!
That is exactly what it is for. We have one on our trailer. As above you should be using a break away cable or chain, I'm pretty sure its law to do so when towing now.
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets