The outside of a lampshade is made of fabric, glass, metal or paper. And, the spider, fitter and a harp and finial can help to affix the lampshade to the lamp base.
A lampshade is a fixture that covers the light bulb on a lamp to diffuse the light it emits.
Lampshades can be made out of a wide variety of materials like paper, glass, fabric or stone. If it is made of fabric or paper, it requires metal frame to hold the material in place.
Spider fitters are set on top of a lamp harp, and secured with a finial. Uno fitters are attached to the lamp itself below the light bulb. The harp is typically seated below the socket.
A spider fitting requires a harp and a U-shaped piece of metal with a screw on the top. The harp can slide through the opening in the spider with the screw. Besides, this screw allows you to screw the finial onto the top to secure the lampshade in place.
You have to use the same kind of fitter for lampshade and lamp base.