The original R-5 wall system was delivered with 1″ of DOW insulation with an R-value of 5. The Xi wall system has 2-1/2″ of DOW insulation which has an R-value of 12.5. The Xi Plus wall system is available with an R-value of 21.3 (US markets) and 23 (Canada). Please check with your local Superior Walls supplier for availability, as not all Superior Walls products are available in all market areas.