Our PVC closed-cell foam has a Shore A Durometer of 35 ± and weights 35 pounds per cubic foot.  The thickness is 3/8 in and is strong enough to walk on without major distortion due to the cells or bubbles not being broken; they resemble inflated balloons or soccer balls, piled together in a constant configuration.  This makes it strong and flexible because the bubbles are strong enough to take a lot of pressure, like the inflated tires that hold up an automobile.  Also, the nitrile provides a non-slip surface.  Excellent for light weight applications.