Automatic drop-down seal for sealing a gap between a door leaf or window casement and a mating surface, with a retaining means, a slider, a sealing strip (31, 4), which has a sealing element, and at least two pivoting arms, - wherein the retaining means can be secured in particular to a door casement or a window casement, - wherein the sealing strip (31, 4) can be displaced transversely to its longitudinal direction between a release position, in which the sealing element is removed from a mating surface, and a sealing position, in which the sealing element bears against the mating surface, - wherein the pivoting arms are pivotably mounted on the sealing strip, - wherein the pivoting arms are arranged such that they are pivoted by a movement from a first position to a second position, whereby the sealing strip (31, 4) is displaced from the release position into the sealing position, and are pivoted from the second position into the first position when the sealing strip (31, 4) is moved from the sealing position into the release position, and - wherein the slider, the sealing strip (31, 4) and the pivoting arms form a parallel guide rod, characterized in - that the seal has a return spring, - wherein the return spring is arranged such that it is tensioned when the sealing strip (31, 4) is moved into the sealing position and is released when the external force is removed from the slider, - wherein the sealing strip (31, 4) is thereby moved from the sealing position into the release position and the pivoting arms are pivoted from the second, pivoted-out position into the first, pivoted-in position, - that the seal has a slider, - wherein the slider is linearly displaceable in its longitudinal direction in the retaining means, - wherein, in order to displace the sealing strip (31, 4) from the release position into the sealing position, an external force directed in a first direction can be introduced into the slider, which force is transmitted at least in part to the sealing strip (31, 4) via the pivoting arms, and - wherein the displacement of the sealing strip (31, 4) from the sealing position into the release position moves the slider against the first direction. - wherein the retaining means can be secured in particular to a door casement or a window casement, - wherein the sealing strip (31, 4) can be displaced transversely to its longitudinal direction between a release position, in which the sealing element is removed from a mating surface, and a sealing position, in which the sealing element bears against the mating surface, - wherein the pivoting arms are pivotably mounted on the sealing strip, - wherein the pivoting arms are arranged such that they are pivoted by a movement from a first position to a second position, whereby the sealing strip (31, 4) is displaced from the release position into the sealing position, and are pivoted from the second position into the first position when the sealing strip (31, 4) is moved from the sealing position into the release position, and - wherein the slider, the sealing strip (31, 4) and the pivoting arms form a parallel guide rod, - that the seal has a return spring, - wherein the return spring is arranged such that it is tensioned when the sealing strip (31, 4) is moved into the sealing position and is released when the external force is removed from the slider, - wherein the sealing strip (31, 4) is thereby moved from the sealing position into the release position and the pivoting arms are pivoted from the second, pivoted-out position into the first, pivoted-in position, - wherein the return spring is arranged such that it is tensioned when the sealing strip (31, 4) is moved into the sealing position and is released when the external force is removed from the slider, - wherein the sealing strip (31, 4) is thereby moved from the sealing position into the release position and the pivoting arms are pivoted from the second, pivoted-out position into the first, pivoted-in position, - that the seal has a slider, - wherein the slider is linearly displaceable in its longitudinal direction in the retaining means, - wherein, in order to displace the sealing strip (31, 4) from the release position into the sealing position, an external force directed in a first direction can be introduced into the slider, which force is transmitted at least in part to the sealing strip (31, 4) via the pivoting arms, and - wherein the displacement of the sealing strip (31, 4) from the sealing position into the release position moves the slider against the first direction. - wherein the slider is linearly displaceable in its longitudinal direction in the retaining means, - wherein, in order to displace the sealing strip (31, 4) from the release position into the sealing position, an external force directed in a first direction can be introduced into the slider, which force is transmitted at least in part to the sealing strip (31, 4) via the pivoting arms, and - wherein the displacement of the sealing strip (31, 4) from the sealing position into the release position moves the slider against the first direction.