Ramada windows | [quote] definite steel doors | steel doors definite provided by gorgeous windows. We are Shijiazhuang gorgeous Door (www.sjzygf.com) here: specializing in Shijiazhuang, Hebei: Shijiazhuang sun room, bridge aluminum doors and windows, shower room, steel doors and glass partitions Disadvantages: 1: PVC Material Steel is bad, it must be in the attachment to increase the hardness of the steel. Plastic shortcomings. 2: fire performance slightly worse, if definite steel doors offer, recommended for use in fire protection requirements under conditions of relatively high in the case of aluminum alloy. Plastic shortcomings. 3: Plastic material brittleness definite steel doors, aluminum compared to heavier, would toxic emissions when burned. Steel doors and aluminum doors and insulation performance comparison: thermal insulation aluminum windows inferior steel windows is good, but better than both the heat transfer coefficient of the entire window is only 1.36 times (single window) and 1.44 times (single-frame double glass windows). Steel doors and aluminum windows and doors lighting performance and sound insulation performance comparison: daylighting performance plastic steel doors and windows installed definite difference than aluminum windows, which frame a single member blackout area 10% larger than about aluminum windows, poor vision and decorative effect, is not conducive to Architectural lighting energy consumption, the level of aluminum windows and cracks sealed plastic windows are basically the same, its acoustic performance is basically the same.