If you want us to help we need a picture of the sofa I for one do not like having to go on a search for what you are talking about.

Apologies, here it is...

Can’t help you out with recommending one that looks like it. Are you positive you want one single seat cushion? The reason I ask is that the cushion cover tends to slip and so the seams get all skewed. If you’re okay with having to regularly “untwist” the cover, that’s okay....just wanted to let you know this might be an issue. Some manufacturers claim to have non-slip cushion covers (depends on the backing that’s applied to the fabric). Best of luck with your search.

Thank You!