AJ37 Sheetsdescription：AJ37 double-layer small-hole aluminium alloy shutter sheet has the effective width of 37mm and small holes of 20mm*2.3mm at the hook, with the gap of 30mm. enough for day lighting and ventilation. The distance between holes is 30mm. The shutter sheets are mainly used for the theft prevention and heat insulation of balcony and window, and also used as shade curtains. with the operative width not more than 2500mm.