Device for distributing and directing air, particularly for motor vehicles

This device comprises an elongated duct (1), having in a flat bottom (2) two longitudinal air outlet openings (8, 9), and a single flap (10) laterally movable for obscuring the openings, pressed against the inner surface by a spring (14); a rack mechanism (11), shaft (13) and toothed wheels (12) for balancing and maintaining parallelism of the flap (10), is provided to keep the flap in its longitudinal orientation during its lateral obscuring movement.