Abstract: A gasket for sealing the gap between two approximately parallel sealing surfaces which are displaced axially relative to each other during the assembly, during which the gasket follows one of the sealing surfaces and is compressed between said surface and the other sealing surface. The gasket body which is made of a soft elastic material, for example rubber, consists of two main parts (1) and (2) which are connected through a narrower connection part in such a manner that the sliding part (2) can pivot relative to the attachment part (1). To avoid a relative rotation of the gasket parts such that the assembly becomes unsuccessful, the axis of the connection part (3) extends diagonally from the point of attack (A) on the sliding part (2), towards the supporting surface (7) on the attachment part (1). The sliding part (2) may have a concave surface (4), and the connection piece (3) can have a less stiffness than the sliding part (2). The attachment part (1) can be connected to a reinforcement (17 ).