Chain On A Trailer?

[wotty59]

what type on chain do you need on a small trailer?

[Buenchico]

It's hard to answer your question without a little more detail about exactly what you're referring to here. The timing of your question suggests that you might be in the USA, rather than in the UK (where this website is based), so your definition of a 'small trailer' might not be what we Brits understand by that term. To a Brit, a 'small trailer' probably looks something like this
https://tinyurl.com/y9v9jn5j
whereas an American might be thinking of something like this
http://tinyhouseblog.com/wp-content/uploads/2012/05/serro-scotty.jpg

Further, it's not clear exactly you want the chain for. While US legislation requires the use of a safety chain when hitching up any form of trailer, there's no similar legal requirement in the UK.

However UK law does require that all braked trailers (including caravans) manufactured since 1992 are equipped with breakaway cables:
https://www.westerntowing.co.uk/acatalog/Breakaway-Cables.html

So my current best guess (based upon the limited amount of information available to us) is that it's a breakaway cable that you need but some further info from you might help to make things clearer (so that we can provide a definitive answer to your question).