The Concealed Door Closers offer adaptability to almost any installation. The compact body of the concealed door closer permits its use where a larger closer would be prohibitive. Versatility allows installation in thin slab concrete subfloor construction. A wide selection of interchangeable spindles makes the concealed door closer suitable for virtually any floor covering or threshold application, such as Wooden Door, Passage Door, Metal door, Interior Door, Outer Door, Swing Door etc.The material is Die-casting Aluminum. It is invisible when door closed. When the door is closed the Door Closer cannot be seen or tampered with.