Oh they are a real pain. We have one for travelling the stallion with anything else. I am afraid you will find they are really flinsy and beak constantly!! The ribber hooks onto the hooks at the top pf the inside of the trailer. We have added our own fittings on tho to make it more robust
The rubber straps on mine have perrished within a year (!) and I don't fancy paying over the odds for another lot from ifor williams... What do you use instead emlybob? The rubber on the hooks uses to pin the partitions back for loading/unloading have also perrised
I call them rubber bungies. Rubber covered in thread (so can be diff colours), with a hook on each end. Come in diff lengths, and I assume from a hardware shop. We use for holding partitions back in the lorry.
Caravan/camping people prob use them for all sorts of stuff.