Seller got back to me. He contacted Givi who advised the fitting kit is to be used.
Just been out on a run with the new screen fitted. Well impressed, about a 95% improvement on the original screen. Virtually no noise up to illegal speeds.
Very slight bit of buffeting when you get above 70ish. Small price to pay considering the comparison to the original. Rode the last 20 miles at about 60/65 and had my visor up.
Well happy.