Invisible Shelf Bracket - Black metal bracket with a diameter of 1.27cm, 15*15cm and a wooden board with a thickness of 2.5-4cm are recommended. Sturdy Brackets - Cast iron wall brackets make it easy to fix wooden shelves and maintain balance. UPGRADED RUSTIC SHELF BRACKET - The increased thickness of the metal support rods makes the shelf bracket stronger and can hold up to 50kg+. Wall Shelf Bracket Set: These hidden shelf brackets are made of high quality metal and come with all necessary screws. Black Metal Bracket - Powder coated finish improves corrosion resistance and prevents rust.