These No-Drill Glass Shelf Clamps are made of solid brass with a beautiful chrome or gold plated finish. They make mounting small glass shelves directly to walls or inside cabinets easy becauseylon set screws secure the glass, so absolutely no glass drilling is required. The Round Clamps come in two diameters, 25/32" and 15/16" (19.8 and 23.8 mm) for 3/8" and 1/2" (10 and 12 mm) glass. Maximum shelf protrusion from the wall is 5" (127 mm). Shelf Clamps are also suitable for use with small acrylic or wood shelves. All Clamps have a single mounting hole. Sold one per package.