This is an adaptor to convert the top part of a glass, as you see on the image, to ab E27 Lamp.
Determined by take care of the temperature. Dont,t use more than 30W! It's designed to use with low watt deco lamps or LED.
The glass can be found at IKEA at distinct sizes of this sort with the exact same metal clasp.
The lamp outlet is also accessible at IKEA in types and different colours.