Hi karalu,
It’s unlikely you will be able to find out all the information you will need to make an informed choice with most of the major brands such as Sealy and it’s probably best to avoid them altogether (see the guidelines here).
The best place to start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how and why to avoid the worst ones (including any mattress where the information here isn’t easily available to you).
“Blind” purchases are much too risky and one of the biggest reasons for buyers remorse with a mattress purchase.
Phoenix