What is a harp? Harps are what we call those flexible U-shaped metal wires that connect the lamp base to the lamp shade. Most harps have a small metal cap on each end to prevent the harp from slipping off the socket. A harp gives the added bonus of protecting the bulb from accidental breakage.
Often people buy a new harp when fitting a new lampshade. If you buy a shade EXACTLY like your old one, you should not need a new harp. Luckily, most harps are interchangeable, so if your new shade does not fit perfectly at first, switching the harp is easy and can usually get you a perfect fit.
If you need a different size harp, first remove the finial and you should see a number stamped into the top plate of your harp. This number indicates the height (in inches) of your current harp. Now you have a reference point and you can measure how much higher or shorter your new harp should be. Another way to raise the shade is to get a shade-riser, which we carry in 1" or 2" models.
How to find the perfect harp size every time? You will know that you have the perfect harp height when you look across the bottom of the shade and the socket is almost visible. If your harp is too tall, you will see the socket. If the harp is too short, you will have to reach up too far to turn on the light.The LampsUSA Harp Fitting Formula is Harp Height = [Shade Height] - [Drop] - [1/2"]. Take the total shade height and subtract about a 1/2" (to make sure the socket is not exposed). Then subtract the "drop", to find the drop measure from the top of the shade down to the center of the spider. Most shades have drops of about 1". However, some taller shades have drops of 3-4". This can really affect your harp size, be sure to measure this before ordering.
just what i was looking for
bought this harp to adjust the new shade for a better fit. Worked as expected.