When it absolutely, positively has to be aluminum, Blomberg is the manufacturer to consider. They have 300+ proprietary extrusions (essentially a lot of ways to make their frame rails strong and durable with a beautiful finish). Aluminum is their passion. It’s the only frame material they use in making windows, doors and glass wall systems. The energy performance ratings on their products is best in class, be they single, dual or triple pane. The frame profiles for some of their window and door products are the slimmest in the industry – 5/8” for windows, 1.25” for doors. Blomberg was founded 60+ years ago in Sacramento. The company is currently owned by an architect.