This 27W compact fluorescent light bulb is very bright at 5500K color temperature with 1300 Lumens output. The Joyous Light bulb is daylight balanced, i.e., its brightness is equal or very close to daylight, which makes it ideal for treating S.A.D. (Seasonal Affective Disorder) a.k.a. "Winter Blues." Customers praise the bulb"s brightness that makes reading texts easy on the eyes, renders colors of objects accurately for photography, and helps to improve the mood. It is also great as a task light or grow light bulb. Energy Star compliant, flicker-free, CRI of 91, bulb life up to 10,000 hrs.*) Fits all medium-base E27/E26 sockets. Dimensions: L: 6.5 in; W (Diameter): 2.5 in; Length socket base to top of ballast: 3 in; W (diameter) of socket: 1 in. Important: *) ALZO CFL bulb life is based on the bulb in an open air upright orientation. When ALZO bulbs are installed in fixtures that lack adequate ventilation, the life of the bulb will be reduced. If an ALZO CFL bulb is installed in an overhead recessed light fixture with the bulb glass below the base, the life of the bulb will be greatly reduced. ALZO warranty for all CFL bulbs is 30 days. Combine with: • ASIN B0035LTIZE; a larger lamp harp might be needed to fit this bulb, such as the ALZO 9 inch harp • ASIN B0089MIH8I; also available as a 15W bulb