Abstract: A value incorporated into apparatus for controlling rigidity of a vehicle seat includes a housing defining a bore terminating in first and second counterbore ends with a narrowed central portion therebetween. A first port through the housing opens into the central portion, while a second port opens into both counterbore portions at or near the junction with the central portion. A two-piece resilient sealing member is disposed within the bore, and has enlarged first and second ends positioned in sealing contact within the counterbore portions to seal the bore, The sealing member is also normally positioned in sealing contact with the junction areas to seal the central portion from the counterbore portions. The sealing member may be moved longitudinally within the bore to move one of the enlarged portions away from one of the junction areas to open a fluid flow path between the ports. Normally open electrical switches are provided to be actuated upon longitudinal movement of the sealing member.