This company provides what appears to be a thorough and complete demonstration of a window, with claims that it will save you up to 40% on your heating and cooling bills. The guarantee that they use has a tiny disclaimer that they will reimburse you up to $ 500.00 if these windows do not perform as specified. I have had these windows installed for the last 2 or 3 years and saw NO CHANGE in my heating and cooling consumptions as a result of the installation. These are very expensive windows and DO NOT PERFORM as you will be told. DO NOT PURCHASE PENGUIN WINDOWS!! THEY DON'T WORK!! read full review »