Ventilation kit for cooker hood (Norton DY8)

Cookerhood Ventilation Kit 150mm diameter duct. New parts but with the original flexible duct piece replaced with flexible PVC one 1m long. (Original Manrose brand parts kit bought from Wickes). So now parts in kit (as photo): 1m PVC 150mm diameter duct; 1 x grey gravity flap vent outlet; 1 x set of wall plugs and screws; 1 x 150mm to 125mm reducer.