Before installing the hinge, the leaves move too freely, causing a collision sound. After installation, the door and frame provide necessary support and restriction for the hinge to that the leaves move smoothly and silently. High quality construction - Our hidden door hinges are made of stainless steel to durability. Advanced technology, reliability and safety - the concealed hinge is made by integrated laser welding process, which has higher durability, bearing capacity and wear resistance. Additional built-in gaskets and sealed bearings that the installed door can be opened and closed quietly. Hidden design - Our hidden door hinges are specially designed to be hidden in view and not stand out when the door is closed. Our hinges mean that you can use this heavy-duty hinge, whether your door is left-handed or right-handed. This requires slotting, which is not a standard size, but it is more suitable for DIY hidden door projects! ! ! Easy to install - the hidden hinge is also equipped with 304 stainless steel screws. The high-density self-tapping screw and the hidden hinge of the door complement each other, and the threaded hole and the screw go back and forth, so that the bite is not easy to loosen and deform. Widely used - stainless steel wire drawing. Our hinges are suitable for wooden doors, swing doors, secret doors, aluminum doors, fire doors, smoke doors, sound-proof doors, security doors and so on., Manufacturer: PokFhgur