If your lampshade is for a pendant light, you will need a Spider Converter.
This attaches to the bulb holder on the hanging ceiling flex, and is secured with the threaded ring. The lampshade is then placed to sit on the three angled prongs.

This fitting will work for both BC and ES light fittings by using the provided Converter Ring.

This accessory is required for Tall Tapered lampshades, and Medium, Large and Oversized French Drum lampshades.