Large car roof box
Roof BAR mounts only - NO CROSS BARS AVAILALBE AT PRESENT!
Will not fit lower, integrated bars without gaps.

NOTE: Your car Insurance. A roof box might be a ‘modification’ depend on individual insurance companies interpretations and may also depend on if its a permanent addition or something put on/taken off.

A quick google shows the likes of Churcihill do count it as a vehicle modification and therefore should be declared. The consequences of having not declared it will depend on what your insurer's response would have been had you declared it before the incident. YOU MIGHT NOT BE INSURED!