Wouldn't that be a King size in the US? They usually hold two twin size mattresses over a larger box spring.

Thank for the suggestion!!

IKEA

Also, might be a Cal King, which is slightly bigger. Why not make your own? It's doesn't have to be expensive and it's not difficult to do. Check out "how to" videos on Utube. You can learn how to do anything there. Then you can create exactly what you want and need in the colors and fabric you decide.