F50 Curtain Wall Classic Semi-Face View System The logic of this system is similar to the classic F50 facade system, with the difference that in this system, only one of the horizontal or vertical caps can be used in the exterior of the building. In seams that do not have a cap, rubber or silicone adhesive can be used upon request. By choosing different caps in smooth, round and oval shapes, you can give a different atmosphere to the building facade.