The teams run their cars here with less aerodynamic downforce than at any other circuit and finding the right balance between straight line speed and cornering is key.
The device reduces the car's drag on the straights, allowing them either to have fastest straight-line speed for the same cornering pace, or to run more downforce in the corners without a penalty down the straights.
The F-duct normally improves straight-line speed but at Monza it is helping to improve cornering speed while the flatter, Monza-spec wing actually makes the car quicker on the straights.