This is a threaded skirt that will screw over the top of the standard E26 brass lampholder, allowing you to use 2x shade rings to hold a shade into position.
For the lampholder search: 4676844 or 5005073
And for the shade ring search: 38065
Please Note that the lampholder and shade rings are not included.
Internal Diameter: 35mm
External Diameter: 38mm