Do you know what is lamp shade spider fitting?
A lampshade spider is made of metal arms. Attach the metal arm to the inside top rim of the lampshade. Connect it to a hollow round metal disc that looks like a washer. We also called spider fittings as “washer fittings.”
Harp is a “U” shaped piece of metal. Slide the two ends of hard into a saddle, a bracket which can be attached to the socket of the lamp base.
To attach the harp and the shade together, you need to turn to the finial. Push the screw attached to the top of the harp through the round central piece of the spider and the finial threads onto it. Secure the shade to the harp.
You need a shade with a spider fitting if there is a harp and finial attached to your base or a saddle affixed to the socket of the lamp.
Both clip fitters and UNO fitters allow the lampshade to attach to the lamp without using a harp and finial.