I bought 2 of these for use on my new day bed with trundle.  They fit perfectly and were pronounced very comfortable by my guests.  They arrived in a surprisingly thin, easily handled box.  .They did require a few days before they puffed up and the chemical smell dissipated .

Pros: conveniently delivered (free) to my home in an easily handled package. Puff up to comfortable size.
Cons: Need a few days to air out.