Not a great fan of f-ducts on F1 cars. I personally don't like how the cars look with the engine cover connected to the rear wing. Probably not safe what with the no handed driving and all. Following more meetings in Barcelona, Formula 1's team have made the unanimous decision to ban the f-duct device from the 2011 season onwards. The radical feature, first introduced by McLaren, allows drivers to stall air to their car's rear wing and therefore allow greater straight-line speeds.
With the Formula One Teams Association (FOTA) having gathered in the Circuit de Catalunya paddock, it is believed that McLaren was against outlawing the f-duct - since introduced by Sauber, Williams and Ferrari as well - although teams did eventually reach the decision universally courtesy of a voting process.
Using an air vent which is located on the top of the car's monocoque, drivers are able to cover a hole (with their knee, in McLaren's case or with the back of their hand, in Ferrari's case) in order to decrease the amount of air which travels to the rear wing, meaning that there is less downforce and therefore higher top speeds on straights.
As there is no moving mechanical part necessary, the device is legal under the current FIA technical regulations but will disappear once the current campaign comes to an end.