Yes, it will take standard Edison screw based bulbs. It is shipped with an Edison screw based CFL, but you can use a standard A-19 bulb if you wish, perhaps in conjunction with a dimmer switch.
By R. Frary on February 2, 2014
I don't know the exact answer, but it did fit perfectly on my Hunter Fan. I don't want to uninstall it to measure it, but it seemed like a very universal size. I hope that helps. It does work well now that it is in place.
By Amazon Customer on November 13, 2014