Inner foam specifications:
The best way to know is to check the package for the density of the foam.
Cheap foam density normally is 10-15kg/m3. density, mid-grade foam is 18-22kg/m3.
High density and good foam is over 25kg/m3. density.
Usually, 27kg/m3 foam is considered the ideal density to properly support the human body and compressed roll up packaging.