I used them to make a camera lamp. The harp worked great, but the harp saddle (lower part) was too small to fit on the base of an IKEA lamp. I had a separate European saddle and the harp fit into it. That was excellent!
Pros
Note: Please make sure your E26 lamp base with collar ring (like the pictures) so the lampshade height must be more than 10 inches. Dedicated to E26 Lamp Holder Converter Detachable Lamp Harp