Need Mattress measurements 2003 Star Craft 21rb

That sounds right to me. Yes, the mattress is two foam pieces inside the cover, one for each half. It ends up being hinged by fabric in the middle so it can fold and sit on the bunk shelf when the bunk door is closed.

Well, in my case it's two even halfs. On yours, one side is wider than the other so it doesn't fold exactly in half.

Ray