A flap provided with an integral motor-containing drive element provided with an integral motor-containing drive element for controlling the air flow through an air-guide duct in, for example, a motor vehicle air condition system which includes a housing defining an air flow duct, an evaporator located in the housing, a heater located in the housing. The flap is adapted to be pivoted about and axis and is supported at each of its axial ends. One end is provided with a cut-out or recess which extends inwardly from one end along the axis of rotation. This cut-out or recess has opposed edges which engage in slots formed in holding means or housing that encloses the drive element, and which permit the ready insertion of the drive unit into an operative position.