A blade (70) for a lawn mower (10) includes a blade body (162), a longitudinal axis, a center opening (166), a first aperture (172), and a second aperture (174). The blade body (162) has a first end and a second end opposite the first end. The longitudinal axis extends centrally along the blade body (162) and through the first and second ends. The center opening (166) is defined in the blade body (162) and receives a drive shaft (128). The first aperture (172) is defined in the blade body (162) between the center opening (166) and the first end. The first aperture (172) receives a first projection (150). The second aperture (174) is defined in the blade body (162) between the center opening (166) and the second end. The second aperture (174) receives a second projection (154). The first aperture (172) has a different shape than the second aperture (174). A centroid of each of the center opening (166), the first aperture (172), and the second aperture (174) is substantially aligned with the longitudinal axis.
