WTB Air kill

Wanting to buy a air kill for a 5.5 inch cover. Thanks
812-605-2375

I have a goofy aircraft isolation butterfly valve that's around 5.5" inner diameter and 6.5" outer diameter. It looks sorta like the attached picture. It's bulky and would take some fabrication to make work, but it wouldn't pull in outside air and doesn't weigh much. I'd sell it for, oh, $50. Let me know if you're interested in pictures of measurements.