This is a Chrome BC Switched Lampholder with 1/2" thread in the base and a shade ring. Used with a standard B22 lamp. This Chrome Plated Switched lampholder will fit onto a 1/2" male thread.
Comes complete with a shade ring and will fit a shade with a 28-29mm hole.
As this is a metal lampholder, ensure you use a 3 core mains flex to provide an earth connection to this lampholder.