17 exert an opposing force on each of the two sides affected by engagement with the male element in a non uniform manner as shown by their deformation which is practically total on one side of the projection 10 and more or less non existent on the other side this situation may occur at the minimum limit of the tolerance range in the opposite case where the perimetral dimension of the seal is at the maximum tolerance limit there would be the reverse situation with a total deformation of the lips 17 on the opposite side of the projection 10 to that shown in fig3 whereas on the other side u2014 that shown in fig3 where the lips are compressed and crushed against 10 u2014 they would be nearly inactive and almost in a rest position without appreciable deformation not shown in the accompanying drawings there are also various intermediate situations compared to the two limit situations shown above where the tolerances present have values which in each case vary with associated deformation of the two pairs of lips which are correspondingly different on the two sides of engagement with the male element and increasingly less dissimilar until the ideal situation shown in fig2 is achieved whatever the case the seal according to the invention is able to compensate for any dimensional deviation which falls within the predefined tolerance range allowing satisfactory stable.