A real double pane! Last year I replaced all the windows in my house with that expensive double-pane energy-efficient kind, and today, I got a call from the contractor who installed them. He was complaining that the work had been completed a whole year ago and I still hadn't paid for them. Hellloooo,............just because I'm blonde doesn't mean that I am automatically stupid. So, I told him just what his fast-talking sales guy had told me last year, that in ONE YEAR these windows would pay for themselves! Helllooooo? It's been a year! I told him. There was only silence at the other end of the line, so I finally just hung up. He never called back. I bet he felt like an idiot.