Metal，plastic or fibre tube fitted to wall, ceiling or under platform of exhibit used as an encasement for electrical le安装在墙里、天花板或在展台地板下面用于包装电线的金属、塑料或纤维管道。
The principal protection is due to the zincs encasement of the item, which prevents contact with the environment.镀锌膜可以阻止产品与外界接触，从而起到保护作用。