If you restore lamps, this is an indispensable part. It screws right onto a standard 1/8" nipple and the center rod can be safely raised to about 2.5" . The standard finial thread at the end of the rod comes with a 3/4" wide flat nut which travels on the 1" thread up or down and gives you added adjustment capabilities. All in all, it's worth the money because now you can buy lampshades with less worry about their overall height.
After posting a question about this item which was promptly answered by Paxton, I purchased this lamp shade extension. Not only was it the exact fix for my lamp, it is incredibly well made, great looking and amazing in every way! I could not be more pleased with this purchase or with Paxton Hardware.