Ventilation duct is a high volume, low margin product, so the coil must run fast, form cleanly and hold a tight lock seam without splitting. This HVAC ductwork galvanized steel coil is specified with a Z120 zinc coating on a draw quality base, thickness 0.5 mm to 1.2 mm and slit edge trimmed to the exact width your spiral or rectangular line requires, from 600 mm up to 1250 mm. The combination of moderate coating weight and controlled surface friction lets the coil travel