The Shade carrier is intended for use where the shade has only a supporting ring, high in the shade and in this case the shade rests (unattached) on the top of a shade carrier, this allows the height of the shade to be adjusted relative to the lampholder, a good rule of thumb being that the bottom of the shade should be level with the bottom of the lamp holder.
The white shade carrier comes in a range of sizes from 5" to 9" this refers to the height from the lampholder ring to the support for the shade on a nominal basis (may vary by a few mm).
The lampholder ring is 1 1/8 inches (29mm) internal diameter and designed for a standard UK bayonet and ES connector lampholders.
The carriers come with an adapter that can be taken off to fit EU lampholders.