... solar thermal collector,25mm Hail Resistance Includes Vacuum Tubes, Heat Pipes, Manifold, Frame,Silica Gel. solar thermal collectorSpecifications: Manifold: Interior: red copper ... x 1.8mApplications: Domestic, industrial and commercial heating use Suitable for open or closed (glycol-water) ... Space heating Caravan parks, hotels, schools, public showers/kitchens ...