Bronze Small Ring With 10mm Female Thread 4794454
This can be used at either the lampholder end or the ceiling plate end.
If you want to use this with a lampholder then you will need a small piece of male thread to go in between this and the lampholder.
For a ceiling plate end you will need something like a pottery nipple PLU86986 or PLU71601
Thread: 10mm x 1mm pitch
Outer Ring: 22mm
Inner Ring: 13mm
Plating Finish: Bronze