Here we have a set of Three Shade reducer rings. These are used to reduce a 40mm (larger hole) to a standard british 28mm size hole on Lampshade, etc.
You will require one reducer per shade, as this type inserts into the large 40mm hole and reduces it to a standard british size 28mm.
Don't forget you are getting a set of three
For bulk orders check other products.
Please note these are injection molded parts so will have some plastic residue from forming. This does not in any way impede there use. (Just FYI)