Our Passport murphy bed is the tri fold type. The next year Keystone when to a full mattress but that blocks most of the basement.
I think they went back to the tri fold.
Anyway, this is our forth season and the mattress which use to be quite comfortable is now a little lacking.
A new tri fold is around $400.00.
I bought this memory foam mattress topper but I put it under the regular mattress.
Fold up the mattress then roll 2/3s of the topper in above.
Works great and is very comfortable. We also tried it as a topper and were still able to fold the mattress and topper all together but I like it on the bottom better.
We got the queen size 3" model. It's just a little long but doesn't matter.
https://www.amazon.com/Cr-Gel-Infuse.../dp/B01NBFBFBM