A seal assembly comprising: a rigid carrier, an elastomeric body, an elastomeric film, the carrier, the elastomeric body and the elastomeric film each having a longitudinal axis and being.coaxial with the other, the carrier including an outer peripheral surface facing outwardly from the longitudinal axis, an inner peripheral surface facing inwardly toward the longitudinal axis and defining a central opening extending longitudinally through the carrier, a lateral carrier surface facing longitudinally in a first longitudinal direction and extending laterally between the outer peripheral surface and the inner peripheral surface, the elastomeric body including a stationary portion and a diaphragm portion, the stationary portion being generally laterally coextensive with the lateral carrier surface between the inner peripheral surface and outer peripheral surface, the diaphragm portion being generally laterally coextensive with the opening, the elastomeric body having a working surface facing in the first longitudinal direction, the elastomeric film being generally laterally coextensive with the elastomeric body working surface, characterised in that (a) the carrier has a plurality of towers (38, 39) each extending longitudinally in the first direction from the lateral carrier surface and terminating at a lateral control surface facing longitudinally in the first direction, (b) the elastomeric body including a first seal bead, the seal bead having an increased thickness and extending substantially around the opening of the carrier, and (c) the elastomeric film being adhered to the elastomeric body working surface, and covering the first seal bead. a rigid carrier, an elastomeric body, an elastomeric film, the carrier, the elastomeric body and the elastomeric film each having a longitudinal axis and being.coaxial with the other, the carrier including an outer peripheral surface facing outwardly from the longitudinal axis, an inner peripheral surface facing inwardly toward the longitudinal axis and defining a central opening extending longitudinally through the carrier, a lateral carrier surface facing longitudinally in a first longitudinal direction and extending laterally between the outer peripheral surface and the inner peripheral surface, the elastomeric body including a stationary portion and a diaphragm portion, the stationary portion being generally laterally coextensive with the lateral carrier surface between the inner peripheral surface and outer peripheral surface, the diaphragm portion being generally laterally coextensive with the opening, the elastomeric body having a working surface facing in the first longitudinal direction, the elastomeric film being generally laterally coextensive with the elastomeric body working surface, characterised in that (a) the carrier has a plurality of towers (38, 39) each extending longitudinally in the first direction from the lateral carrier surface and terminating at a lateral control surface facing longitudinally in the first direction, (b) the elastomeric body including a first seal bead, the seal bead having an increased thickness and extending substantially around the opening of the carrier, and (c) the elastomeric film being adhered to the elastomeric body working surface, and covering the first seal bead.