The harp is too small for anything other than a C-7 bulb to fit. I ended up being stuck using a 90 lumen, 1.5 watt, LED T-5 bulb, which is also twice the cost of the others, but far brighter than the C-7. The lamp itself is beautiful and of nice quality, for the price! I ended up making three trips to Lowes for 40 watt bulbs, that failed to work, though. The G-16.5 was too fat, the A-15 was too tall, as well as the standard B-10. (Yes, I worked at Sylvania, once upon a time, to know the bulb shapes.) All of which are roughly 325 lumens, which is needed with the thick (dark) shade. Unfortunately, I had already taken the box and paperwork to the dump, thinking the second bulb would have cleared the harp. I did notice that the harp doesn't seem to fit quite right in the lamp, like the wrong one may have been packaged. Its beautiful, but just too dim to use as a small desk lamp, with 1/4 of the standard lumens.