Anyone know anything about these? I have a trailer that has the racking bars in along each side at 2 heights, but am struggling to find the right things to clip into it. Ideally I want something like this, but this requires 2x20mm holes to connect to – my racking has alternate 20 and 25mm holes.

Any suggestions as to a cheap supplier?

Have found these
https://www.nationwide-trailer-parts.co.uk/products/square-shoring-bars?variant=1201857437
https://www.allsafe-group.com/en/load-restraint/
http://www.uktrailerparts.co.uk/shoring-bars-and-cargo-stays

Thanks for that. The problem with the expanding bars is that most are too wide for my trailer (approx 1.7m). They also seem expensive compared to the simple hook and bar systems.