OEM:
13-5/8 x 5-1/8 outer dims
Made from 1 x 3/4 x 1/8 Al angle with 1" dimension protecting vent and 3/4 dim under vent lip with screw holes
One corner is mitered and welded then ground outer radius
3 corners have a notch cut out of 3/4 dim, bent to 90 on joint before holes drilled - I would have tacked the hull side of that joint but mine are not.
