These Roman Series 90 Degree Glass-to-Glass Clamps have rounded corners for a "softer" look. The Clamp has an open back so the glass can either be mitered or overlapped. used connect two fixed glass panels meeting at a 90 degree angle, or as a horizontal shelf bracket. Clamps are designed for use with 5/16 or 3/8 inch (8 or 10 millimeter) thick glass. A hole is required in the glass for installation. By utilizing the wood screw that is included, the clamp can be used as a shelf bracket or offset wall mounting clamp.