DuPont™ Styrofoam™ Brand Cavitymate™ Ultra Extruded Polystyrene Insulation is an XPS foam insulation board with an R-value of 5.6 per inch. It features square edges on all four sides that makes it easy to fit between brick ties in cavity wall applications. DuPont™ Styrofoam™ Brand Cavitymate™ Ultra is a key part of the DuPont™ Ultra Wall System, which was developed in response to feedback from architects and masons in need of a consolidated system for cavity walls. The Styrofoam™ Brand XPS product line gives you the proven thermal and moisture performance of the original XPS, plus the product options you need to design and build energy-efficient, resilient structures all the way to the top. It's lightweight and easy to install, which makes the job go faster.