Material: Zinc alloy embryo + aluminum alloy core. Coated with matte black finish. Concealed door hinge for doors are made of solid zinc alloy by precision die casting. It is Sturdy, corrosion resistant and has a long service lifeHidden DesignHeavy-duty 180 degree Hidden hinges meet ANSI/BHMA standards, perfect for any commercial or intensively used door, including wooden doors, flush doors, metal doors, fireproof doors, noise isolation doors, security doors, etcPackage: 4 sets of 180 degree opening invisible hinges, individually wrapped to protect against scratches, includes screws,decorative cover,and adjustable tool for installation on any type of doorNote: Each Hidden door hinge must be filled with 4+4 screws. Screws are free products, if they are not enough, please purchase them separately3-Way Adjustability: vertical 3mm, horizontal 2mm and depth 1 mmDimensions:6 x 2.5 x 1 inch. Each hidden door hinge measures 6 inches x 2-1/2 inches x1 inches, standard template hole locationsDoor Size:Minimum thickness of door leaf: 35mm -40mm,Maximum width of door leaf: < 1000mm