A shoe is a stack of decisions.
We show mechanisms and qualitative changes, not calculated grams, grip scores or years of service. Thickness and density comparisons hold the material recipe and footprint fixed. If changes pull mass in opposite directions, the total remains unresolved.
Airflow and water-vapour transfer are different. Softness and bending flexibility are different. Ground protection and slip resistance are different. A favourable change in one does not prove improvement in another.
Foam families do not have one universal density, rebound or lifetime. Finish, layer thickness, load, climate, adhesive bonds and geometry can change the result. Actual performance needs evidence from the completed shoe.
The illustration is an editable construction diagram, not a manufacturing drawing or a real catalogue model. Motion exaggerates mechanisms; it does not measure the shoe.
Primary sources behind the mechanisms
Laces, heel counter, collar and the fixed construction board stay in place. Removing the footbed never removes the structural base.