2.500 in. mounting hole center tocenter distance on w, 3.124 in. mounting hole center to center distance on lg, one aperture 0.499 in. min, 0.507 in. max dia 2.062 in. left of center on horizontal centerline, main aperture slotted 1.590 in. right of center on horizontal centerline 0.760 in. w anodize case surface treated