Sporting the thinnest frames, aluminum windows have been making a comeback in recent years for its industrial/contemporary style and expansive glass. While not quite as energy efficient as vinyl, wood or fiberglass, these windows will continue to be in demand. They are also very easily recycled at the end of their service life.
Milgard has been building their Aluminum Series Windows and Doors since their inception in the early 1960's. That deep product knowledge has led to a modern aluminum window that comes with a Full Lifetime Warranty. Surprisingly, it's also one of the less expensive windows in the market today!