The heavy-duty frame measures 2-1/8” x ¾”, which is constructed of extruded aluminum and is stronger than roll-formed steel frames. The rigid LOK-titeTM corners ensure that the Ocean View doesn’t flex, and provides stability. Oilite bearing hinges are fastened to the expander channel with aircraft quality rivets. The heavy duty quiet pneumatic closure is guaranteed for 10 years. The pushbutton lock is the highest quality as well. Standard 18x16 charcoal fiberglass insect screening helps keep the bugs out, while letting the air in.