U Hooks (Henley-on-Thames RG9)

I think these are called U hooks but I've tried Googling and can't find anything similar. The metal U's are removable but can be fixed in. The three on the right are made by Thule, and were used inside roof boxes to hold the roof bars in place. The old roof box we had needed six. I don't think they are made like that now. I can't now remember why we got two types, especially as they are the same size - 3.5 inches/9 cm wide. They are pretty strong and could be used for a variety of purposes to hold things firmly in place. In the Thule ones the plastic top turns to fix the hooks in place and in the others the hooks are held in place by turning two knobs. In case the photo isn't clear there are three of each.