1) Outside is zinc-plated steel planks; high performance and rustproof
2) Thickness: 40/50mm
3) Door is steel/polyurethane/steel construction
4) Heat insulating coefficient: R=16.04, R=20.15
5) The U-tube rubber at the bottom along with the top and side seals are
tight, keeping out wind, dirt and water
6) All the metal tightening parts are made of zinc-plated steel
7) Twisted spring can be used for more than 100,000 times
8) Glass window is made from toughened glass and organic glass
9) It has a quick-stop system
10).Optional air bag