The sturdy metal structure is made of thick, high-quality materials for durability. The surface is specially treated to resist rust and damage, ensuring long-lasting performance with fine workmanship. Base supports up to 570 lb (260 kg). Constructed with high-quality materials, excellent forging process, scientific structural design, and secure screw fixation. The hinge provides stable and strong door support. Features up and down linkage function. When installed on the central axis of the door, it allows 360-degree rotation; when mounted on the side, it enables 180-degree rotation, suitable for various installation styles and applications. Precision-engineered base bearing design ensures quiet, smooth, and flexible door movement. Compatible with wooden doors and aluminum frame doors. Ideal for use with hidden doors, heavy-duty doors, secret doors, hidden door bookcases, bookshelf doors, swing doors, hidden shelf doors, and standard door hinge installations. Allows customization of hidden door solutions. Installation is quick and simple with all necessary hardware included. Material: Metal Color: Black Package Contents: 1 set hidden door hinges Note: Other items not included. Lighting and display differences may cause slight color variation between image and actual product. Measurement tolerance: +/- 1-3 cm.