This is a Antique Brass BC Switched Lampholder with 1/2" thread in the base and a shade ring. Used with a standard B22 lamp.
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.
Please Note: This 1/2" lampholder will NOT fit the 1/2" BSP gas pipe, BSP gas pipe is alot larger in diameter and is a totally different thread style.