The present invention concerns a seal comprising a front fitting (1, 21, 41), a rear fitting (2, 22, 42) and a compressible part (3, 23, 43). The compressible part (3, 23, 43) is placed between the front fitting (1, 21, 41) and the rear fitting (2, 22, 42). The seal is a transition for a conduit through a wall (16), wherein the conduit is received in a central through opening of the seal and wherein the seal is received in an opening of the wall (16). In a mounted seal the compressible part (3, 23, 43) seals inwards against the conduit and outwards against an inner surface of the opening of the wall (16). The axial extension of the compressible part (3, 23, 43) is larger than the thickness of the wall (16) at the opening of the wall (16).