The mattress is a perfect fit for my very old futon frame.  It had a slight odor when I opened the box, but that has pretty much gone away.  I laid the mattress flat for a few days.  After that, I took the mattress off & put the frame in the "couch" position & when I pushed the mattress into the folded position, it stayed that way without any problem.  The cover is not removable.  I have had the cushion for about a month.