Usage Tips: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 comePRACTICAL 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 nearlyhidden from viewEASY 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 doorWIDE 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 concernBUY WITH CONFIDENCE: With compact design and solid construction, these rotary door pivot hinges make a nice accessory for your door hardware.