NIUNIU STURDY AND DURABLE: Made of heavy duty stainless steel with maximum corrosion resistance and durability, the hidden door center pivot hinges are made to provide reliable support for years to come PRACTICAL AND INVISIBLE: With unique roller ball design, these 360 degree rotating door pivot hinges provide a simple and effective way to swing the door easily and quietly. Solid rotation door hinge with heavy duty design and smooth bearings is nearly hidden from view EASY INSTALLALTION: The top pivot comes with retractable pin for quick and easy installation. The rotation hidden door pivot hinge can be mounted on the top level the door and is attached to a hole on the surface of the door WIDE APPLICATIONS: The concealed rotating door hinges work wonderfully for swinging doors, murphy doors and so much more. Excellent pivot set option when door weight stress on traditional door frame butt hinges is a concern Delivery Quantity: 1set of 2pcs , Package Contents: Only the above package contents, excluding other products. Dimensions: hole spacing 112mm, height 42mm, cylinder diameter 18mm; length 130mm, width 24mm, height 21mm, cylinder diameter 18mm; length 104mm, ball diameter 9mm, cylinder diameter 10mm; hole spacing 86mm, height 20mm, cylinder diameter 16mm (Reminder: The size is measured manually, please allow 1-2 cm measurement error) Color: silver (Due to different monitors and lighting effects, the actual color of the item may be slightly different from the color shown on the picture.)