We have developed our own construction, where we have combined the basic idea with 2 vertically sliding sashes,  placed one above the other in one common frame, with modern technology ( espagnolette and lockable handles in the lower sash, and spring balances to hold the sashes in open position). In this way the window can meet today's requirements for insulation and density against water and wind.

In addition, the SOLBORG sashes are made with internal glazing beads and external silicone sealants so that they  match the casement window sashes design in the VROGUM CLASSIC product line, and can be combined with these  in the same architectural expression. See more about the SOLBORG  construction and performance here.