GLASSESSENTIAL® Security Sliding and Folding Grille System S 525 is cost effective and provides dependable security. System S 525 stands out for its attractive looks.economical and lightweight open style sliding grille. System S 525 sliding grille easily blends with any decor, providing unobtrusive protection. It's fine lines and high visibility makes the System S 525 folding closure an effective barrier, while maintaining a sense of open space.