My 1988 PSC 34 has oval ports as does the 1985 PCS 34 in the adjacent slip. Our oval ports are not the same. To me, his look like the ports shown on the Spartan Marine web site
Bronze and Stainless Marine Hardware, Seacocks, Portholes, Thru Hulls - Spartan Marine Hardware and Accessories
They sell screens for their ports.
My ports are similar but not branded. I made the screens for my ports. They oval plywood rings 1/2" thick and 3/4" wide with a rabbit cut into one side to receive a rubber spline that holds no-see-um screen across the opening in the ring. I made the a pattern for the six large ports and another pattern for the four small ports. When I had the fit right, I copied them with a router and made enough for all my ports. They are stained and varnished to match the interior teak on the boat.
They are bigger than the interior opening in the ports and smaller than the outside opening and wedge halfway in. I glued velvet ribbon around the edge where they contact the port to get a good seal and to keep from scratching off the
varnish.
If I had it to do again, I would probably use tan or brown HMWPE rather than plywood.
I also made similar screens for the two large Bowmar
hatches.
Bill Murdoch
Irish Eyes
New Bern, NC