I need the grill to provide 200cms sq of airflow - can you advise what airflow is provided by the 500x100 grill please?

The airflow of this grille is 178cm2. We don't stock any with this airflow, but if you contact us on 0207 228 1185 or email us - sales@sdslondon.co.uk we can help find a suitable grille for you.