For ceremonial occasions, the president also has access to two special open top Citroën SM Présidentielle models, created for President Georges Pompidou by the coach-builder Henri Chapron. Based on the SM Opera, itself a special edition four-door coupé, these cars are still used for state occasions and military parades, when the open-top layout enables the president to stand in the back seat and survey the crowd. Built for an official visit by Queen Elizabeth II in 1972, the cars have a standard mechanical layout with the addition of a special gear for low-speed cruising. One of these cars was also used by President François Mitterrand for the official opening of the Channel Tunnel in 1994, when it accompanied the Rolls-Royce Phantom VI of Elizabeth II. Number plates on these cars are standard French ones, although specially created for the model ("2 PR 75" and "3 PR 75", '75' denoting the Paris region). Both are still maintained in working order, but are now rarely seen in use.