HUAYU PU ventilation panel is manufactured using a one-pass process in a fully automated continuous production line . The finished product is a polyurethane board sandwiched between 2 layers of textured aluminum foils as upper & lower facing . The facing aluminum foil is treated with special adhesive to ensure better bonding of the layers and is anti - oxidation and corrosion resistant . Special in-line QA and QC system are used to ensure uniformity in finished product’s foam structure , density , insulating property , mechanical strength and dimensional stability .