The F4 is an advanced heavy-duty glazed folding door system, designed for spaces with high aesthetic and practical demands. It consists of panes bearing double glass-boards placed within an aluminum frame for additional robustness, durability and insulation in more demanding and challenging environments. It is therefore ideal where such attributes are desirable. Its vertical profiles have been designed to fit together, bearing male and female sections, so that they perfectly couple with each other, covering all gaps very effectively. Elastic gaskets are also employed, completely sealing even the smallest gaps, for an entirely watertight and airtight result. On its horizontal profiles, water tightness is achieved by using special synthetic brushes, while, around the edges, where the construction meets the surrounding walls on the sides, the F4 employs an additional aluminum profile for even better insulation and a more aesthetically integrated touch. Apart from the floor latches this system uses, each pane is secured and locked with recessed locks found on the vertical profile about one-meter high up from the floor, which is one of the most important features of this model. Any pane can also be turned into an opening/divertible door, functioning as an entrance, once a roof spring mechanism is fit in. Such entrances can be both single and double winged. Depending on the project’s size, the right type of aluminum track guide needs to be selected, for the suspension and movement of the panes: these are either 60x53(mm) or, the heavy-type, 75x72(mm) in size.