I.D. Opening: 9 3/4" x 19 1/2" Cut Out Size: 12" x 21 1/16" O.D. Size: 13 3/4" x 23 1/2"
BOM-81020-W with clam shell vents and a spring to hold it open.
A little worn and a crack on the top of one hinge, but doesn't effect performance.
I'm only dumping it, because I prefer a non vented hatch for where I'm using it.
Make me an offer...plus shipping if you're not local.