A disc recliner operatively coupling a seat back to a seat cushion to allow selective pivotal movement of the seat back relative to the seat cushion about a pivot axis extending in an axial direction, the disc recliner comprising: a first plate adapted to be fixedly secured to the seat cushion, the first plate including a first plurality of teeth disposed therearound; a second plate adapted to be fixedly secured to the seat back and rotatably coupled to the first plate, the second plate including a second plurality of teeth disposed therearound, wherein a tooth count of the first plurality of teeth does not equal a tooth count of the second plurality of teeth; a flex spline including a flexible wall having a third plurality of teeth disposed therearound, wherein a tooth count of the third plurality of teeth equals the tooth count of the first plurality of teeth; and a wave generator gearing (28; 60; 70; 90) having an outer profile causing a portion of the third plurality of teeth to meshingly engage with the first plurality of teeth and the second plurality of teeth, wherein the second plate rotates relative to the first plate in response to rotation of the wave generator gearing (28; 60; 70; 90), thereby causing pivotal movement of the seat back relative to the seat cushion, characterised in that the outer profile of the wave generator gearing (28; 60; 70; 90) includes a plurality of lobes (56; 62; 72; 92) causing the third plurality of teeth to meshingly engage with the first plurality of teeth and the second plurality of teeth in a plurality of distinct regions corresponding with the plurality of lobs, wherein each one of the plurality of lobes includes at least one roller (64, 74, 94) rotatably supported in a recess in the outer profile of the wave generator gearing (28; 60; 70; 90), the at least one roller rotating about an axis generally parallel to the pivot axis, and the at least one roller directly contacting the inner surface of the flex spline. a first plate adapted to be fixedly secured to the seat cushion, the first plate including a first plurality of teeth disposed therearound; a second plate adapted to be fixedly secured to the seat back and rotatably coupled to the first plate, the second plate including a second plurality of teeth disposed therearound, wherein a tooth count of the first plurality of teeth does not equal a tooth count of the second plurality of teeth; a flex spline including a flexible wall having a third plurality of teeth disposed therearound, wherein a tooth count of the third plurality of teeth equals the tooth count of the first plurality of teeth; and a wave generator gearing (28; 60; 70; 90) having an outer profile causing a portion of the third plurality of teeth to meshingly engage with the first plurality of teeth and the second plurality of teeth, wherein the second plate rotates relative to the first plate in response to rotation of the wave generator gearing (28; 60; 70; 90), thereby causing pivotal movement of the seat back relative to the seat cushion, characterised in that the outer profile of the wave generator gearing (28; 60; 70; 90) includes a plurality of lobes (56; 62; 72; 92) causing the third plurality of teeth to meshingly engage with the first plurality of teeth and the second plurality of teeth in a plurality of distinct regions corresponding with the plurality of lobs, wherein each one of the plurality of lobes includes at least one roller (64, 74, 94) rotatably supported in a recess in the outer profile of the wave generator gearing (28; 60; 70; 90), the at least one roller rotating about an axis generally parallel to the pivot axis, and the at least one roller directly contacting the inner surface of the flex spline.