... ,250,300,350,400,450mm 4.Lowest price Mottorised damper ,air condition parts,damperDuct installationMaterial :Galvanised steel 0.6mm or 0.8mm ... penaltyThere is one damper inside the body to stop the air in the duct go through or not5mm thickness insulation stick ... on the body to stop the air leakSize from 100 ,125,150,160,200,250,300,350 ...