The Seido 2 vacuum tube is a high-performance collector using direct-flow technology.

The direct-flow vacuum tube accommodates a thin copper-aluminium plate, called an absorber, which absorbs solar radiation and heats the fluid circulating around the interior of a coaxial tube inserted in its centre, returning by the external cavity in contact with the plate.

These collectors may be used with angles that range from 0º to 90º, besides the possibility of rotating the tubes, which permits any kind of architectural integration in the building, on facades and flat roofs, without installation on racks.