Help identifying the part that attaches my bike trailer to my bike… I need to replace it.

I have a bike trailer I use for both my puppy and my groceries.

It attaches via a post that is screwed onto my bike. The bike trailer has a 2 inch hollow piece that slips over the post, there are holes that need to be aligned to a hole in the post. Having aligned the holes, the part I lost I need to identify is very simple: it is a two or 3 inch piece of metal That is slipped through the aligned holes. On one end there is a hinged, curved sort of hook, like a big letter C. You move the C over so the bottom , unhinged end can be slipped over the tip of the little piece of metal sticking out on the opposite end. This prevents the piece of metal from wiggling out, keeping it all secure. It’s very simple, practical, easy on and off. I lost mine.

I have been using a C clamp instead, screwing the screw part through the aligned holes and tightening. While this gets the job done, it’s much more time-consuming and physically uncomfortable because the screw on the C clamp, and generally annoying. But I don’t know what the piece I lost is called in order to replace it.

Does anyone know what I’m referring to?

Hairpin cotter pin? Bowtie cotter pin?

Wire lock hitch pin.
Though the company that made your trailer may have a different name.

Runner pat is my personal Hero of The Month!

THANK YOU!!