This photo clearly shows the importance of our thermal barrier. We set our West-Prime Thermal Window frame and an ordinary aluminum window frame on extremely cold dry ice to illustrate how cold is transferred through the frame. Notice that the ordinary aluminum window frame, shown on the left, is completely covered with frost. Now look at the West-Prime Thermal Window Frame on the right. Our thermal barrier resists the transfer of cold from the outside to the inside of the frame. And, of course, the same thermal barrier slows the transfer of heat in summer.