Perforated Radiant Barrier Foil - 4' X 250' (1000 sq ft) Perforated, Metalized Aluminum Radiant Barrier - 1,000 square foot roll (4' X 250' 96-97% Reflectivity, 3-4% Emissivity Lowers heating & cooling costs Extremely high tear resistance, Tensile and Elongation (ASTM D882) = 10,890 PSI Installs quickly and easily, just roll out on top of your existing insulation