AJ77A double-layer aluminium alloy shutter sheet has the effective width of 77mm. The design of unique noise-elimination leather lace between sheets well realizes the silence at motion. Thickened and widened aluminum alloy guiding groove reinforces wind resistance of wide span door. It, as a good substitute for the old-fashioned factory building gate, is mainly applicable to large-sized factory buildings and warehouses with the operative width not more than 8,000mm.