These are solid cast brass casters of the highest quality.
They come in three screw plate diameters. A close fit is important for best appearance and strength.
In addition to the center screw, there are three screw holes in the plate itself that make a very solid attachment to a leg.
The 1” plate caster requires #1 screws, the 1 1/8” caster requires #2 screws and the 1 1/2” caster requires #3 screws (not included).