Designing need to consider of the wind pressure causing canvas damage.
Pulleys with wind pressure reducing design, lowering the possibility of canvas damage.
Aluminum alloy in environmental protection materials, which are recyclable.
Aluminum extrusion tracks and retainers, extensible to 30 meters and attachable to walls. Detachable reels, which are convenient to canvas lift and with auto stop function. Utility model patents in German, Japan, and China; Patents in U.S.A.