How to find out out a mattress' memory foam grade?

Mattress Talk General Mattresses Questions
1

I am interested in a mattress from ghostbed as it is on trusted members list.
I was going through the articles on this website and it says " 5.0 lbs per cubic foot and higher is considered to be the highest quality, 4.0 - 4.9 is mid-range quality, and 3.0 - 3.9 is lower quality (and only suitable for toppers or lower budget mattresses). Memory foam less dense than this should be avoided".

I can’t seem to find out what lbs per cubic foot is ghostbed’s mattreess GhostBed Cool Gel Memory Foam & Latex Mattress | GhostBed®
I did come across one review that says “This foam has a density of 2 PCF” Mattress Reviews 2022 - The Top Rated Brands | Tuck Sleep

By the mattress underground’s own guideline, wouldn’t this ghostbed be considered low quality as its PCF is less than 3?

2

Most beds with memory foam on top will usually have a poly foam core and the density ratings for quality on each are not the same.

Memory foam - High quality foam would be 5 lbs/ft3 (PCF)
Poly foam - High quality foam would be 2.5-3 lbs/ft3 (PCF)