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Closed-cell foam has varying degrees of hardness and insulation value, depending on its density. It can be used for insulation or flotation devices. A normal, closed-cell insulation or flotation urethane is between 2 and 3 pounds per cubic foot. It is strong enough to walk on without major distortion.<ref>Building Envelope Solutions, Inc., http://www.foam-tech.com/</ref> Polyurethane foam has an insulating value of R-5.6 to R-8.0 per inch.<ref>Alliance for the Polyurethanes Industry, http://www.polyurethane.org/</ref> <ref>Polyisocyanurate Insulation Manufacturers Association, http://www.pima.org/</ref>

[https://en.wikipedia.org/wiki/Foam_rubber Foam rubber] is lightweight, flexible (in its open-cell form) and buoyant. It can be used for thermal and acoustic insulation. [https://en.wikipedia.org/wiki/Neoprene Neoprene] is a synthetic foam rubber.