High Quality MaterialsThe revolving door hinge is made of high quality 201 stainless steel, which is strong and wear resistant. It opens and closes very smoothly and can be used for a long time. Invisible Design The door hinge is invisible, unlike ordinary door hinges which affect the appearance, it is installed above and below the door and has a hidden and convenient design. Flexible RotationThere is a stainless steel ball inside the door hinge. The smooth steel ball makes the opening and closing of the door more stable and flexible, and can open and close tens of thousands of times. Easy to InstallThe top pivot Comes with a retractable pin for quick and easy installation. The concealed rotation door pivot hinge can be mounted at the top level of the door and is fixed to a hole on the door surface. Widely ApplicationConcealed rotation door hinges work great for swing doors, murphy doors and more. Great pivot set option when door weight on traditional door frame hinges is an issue.