A little more information may help your search. Although as rare as hen’s teeth, there are carbon runners with internal filters. More common, there are carbon runners that require either a modification to the air box to take a cassette filter or fit a sock filter and there are two different sizes, standard road and the larger race. Good luck with your search. Andy
Thank you for your response, I appreciate the help. I would be after a standard road pair but I'd have to double check on the internal details - not sure what my Ducati has but it's a 1999 748 Biposto!
Cheaper still https://www.gbmotoracingparts.com/MobileDetail.php?Prod_ID=57246 I’m fact I’m sure they were considerably more than they last time I checked.