Spiralux Vita-Lite, 23 Watt, 5500K, Screw-in, Full Spectrum Compact Fluorescent Bulb. Works in a standard socket, it is NOT DIMMABLE. Color Temperature 5500K, CRI 91, Length (including socket) 6.125", Lumen 1380, User Hours 10000. Replaces 100 watt incandescent. Full Spectrum, excellent for people, pets (birds, reptiles, etc.), grow light plants, artists, photography, SAD, and graphics. Best color matching lamp available neutral white light with high CRI (Color Rendering Index), sunlight = 100 CRI.