System 6 System 6 System 6   System 6 Curved Wood Extension An interior with the warmth and beauty of natural wood, formed into a gracefull curved beam. Outside, a weatherproof aluminum glazing system is mounted onto the structural wood beams to provide complete maintenance-free protection in a white or bronze finish. System 6 combines the structural strength and versatility of all Four Seasons models, with the warmth of natural wood in a uniquely attractive interior. The use of slow growth northern white pine makes our wood extensions extremely strong and stable, resisting shrinking, twisting and checking that is common with fast growth wood such as southern yellow pine, poplar, etc. Complete selections of options available: doors, windows, roof and side vents and of course shades (shade tracks are built right into the curved beams). 100% of ALL Four Seasons Products Use Tempered Safety Glass! Our glass is four to six times stronger than ordinary window glass and much safeter too. In fact, our tempered safety glass has smooth rounded edges and meets ANSI 297.1-1984 codes for safety. If broken it would shatter into harmless rounded pellets.