Abstract: Steel frames attach to recesses in a wall opening frame. A steel band is spaced inwardly from each of two opposing sides of the steel frame. A series of interconnected vertical and horizontal steel grill members narrower in width than the steel bands extending between the steel bands and between the sides of the steel frame structure on the other two opposing sides to form a security grillwork. A glass rides on the steel bands and straddles the steel bands and the security grillwork to provide a glass wall inside the security grillwork and a glass wall outside the security grillwork. The glass frame slides on roller bearings in the steel frame. The security grillwork can slide with or separately from the glass frame if a lock is provided in the normally closed position.