Abstract: A toilet seat or lid closing device includes a housing having an inner wall. A shaft assembly includes a shaft, movable between first and second rotary orientations. A first part of the shaft assembly is housed within the housing, and includes an outwardly extending blade, having first and second faces, extending outwardly to an outer edge. A portion of the inner wall of the housing and the outer edge of the blade define a variable-thickness gap therebetween as the shaft assembly moves between the first and second rotary orientations. Several openings extend through the blade, the openings covered on one side of the blade with a flexible material to create check valves. The check valves permit relatively free fluid flow through the opening, thus bypassing the blade, when the seat or lid is lifted but at least substantially prevents fluid flow through the openings when the seat or lid is lowered.