Saw these nice air filters for Volvo P1800. Love the Volvo stamping and two hole for my 1800S. I think the inner filter can be replaced, but I am not 100% sure.
Googled around and I found this new set from ebay auction long time ago.
I also found some photos of old Volvo P1800 with the filters fitted on, looks good.
Current bid price already reaches US$71.
Update 20th Dec 2021: The auction ended at US $227.50. Way over the money I am willing to spend for a pair of USED air filters. Not urgent, as my existing set still working fine.