The Ultra-R direct-set window uses Heat Mirror film technology by Southwall Technologies to achieve a center of glass R-value of 20. The film is coated with nanoscale metal particles that reflect heat back to its source, improving insulation, blocking UV rays, and reducing noise. With a total unit R-value of R-9, it is 33 percent lighter than triple-pane products. Hurd Windows and Doors. 800-433-4873.