What’s this on the firewall?

[myskin]

I have a ‘65 Newport Convertible. I was wondering what is this opening on the firewall ? Is it meant to be covered? Appreciate ideas….

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There should be 2. The old covers were rectangle shaped rubber. Not feeling confident I could find new I bought sheets of rubber and cut new ones slightly larger then fastened them with a rivets going through the holes (mine were still there to act as templates)and a small washer.