We have 3 types of Roof Box fittings to attach to roof bars which are shown below;

The Clamp is shown at the bottom & is used on 23 of our roof boxes. Very simple to attach / detach to roof bars.

For the 2 roof boxes which use U bolts, by default we use the Thule Easy Snap U Bolt system (top right) but alternatively the Traditional U Bolt fittings (top left) can be used instead if you prefer. These 2 roof boxes can also have the T bar fitting installed if required.

Both the clamps and U bolts will fit Roof Bars up to 80mm width.