Hi doghousesnoopy,
Yes … you can read a little more about bedinabox in post #2 here
Density is most closely connected to the durability of memory foam and is not directly connected to how firm memory foam feels which depends on many other factors including its temperature response, its response time, and its contouring ability. You can read a little more about the various characteristics of different types of memory foam in post #9 here and post #8 here but these are controlled more by the combination of chemicals used to make the foam than by just the density. It’s often true that for most people 4 lb memory foam will feel firmer than most 5 lb memory foam but this is only based on averages and isn’t always the case. In the case of Tempurpedic for example their 7 lb memory foam feels softer than their 5.3 lb memory foam for most people.
Phoenix