National Hardware N184-556 Spring Door Hinge 3-1/2 Inch Square Corner Brass Material:Steel There are some exceptions like

There are some exceptions like Homecrest or Samsonite which use two layers of material on some of their furniture to slide the slings over an internal frame

Tube size: fits into a 1-5/8" inside diameter base pole

Fits a 1/2" inner diameter hole

For use on smooth hard floors and on tile floors or rough floors in kitchens or cafeterias

Stanley series DP57-1010 bright brass die cast zinc light duty rigid door stops with choke resistant plastic bumper tip

National Hardware N184-556 Spring Door Hinge 3-1/2 Inch Square Corner Brass Material:Steel There are some exceptions like3 1 2 Inch spring adjustable self closing door hinge manufactured with cold rolled steel. Closing speed is adjustable. Fits standard cutouts. Tension is adjustable square corners. Hinge is UL approved for fire doors which must use a minimum of 2 spring and one conventional hinge per door.