VEVOR Double Reflective Insulation Roll, Foam Core Radiant Barrier, 5.5mm 48 in x 50 ft, Double-Sided Aluminum Foil EPE Foam Heat Reflective Shield, Thermal Insulation Roll for Window RV Roof

Hello, the R value is not a fixed value, because it is affected by many factors. According to general conditions, the R value of this product is roughly between 0.2-0.5m²・K/W