I have a 2007 reg ford focus estate with the c-track system and ford branded ‘aero’ roof bars, part num 1429305.

I am looking for a compatible roof box and I am not sure what to go for.

I am concerned because the roof bars I have seem quite flat and wide (like an aeroplane's wing) compared with other bars I have seen in photographs (which look more ‘bar’ shaped) - See the attached picture.

Please can someone give me some pointers on what I should go for?

Many Thanks,
Tom.