ALZO 27W Joyous Light Full Spectrum CFL Light Bulb 5500K, 1300 Lumens, 120V, Daylight White Light Natural daylight balanced color temperature of 5500K with 1300 Lumens output, 120V; CRI of 91; great for reading, for various tasks and also as a plant grow light This is a large bulb that might not fit standard household lamps, see diagram above; Dimensions: length: 6.5 inches; width (diameter): 2.5 inches; width (diameter) of socket: 1 inch.; fits all medium-base E27/E26 sockets Generates very little heat; all ALZO Joyous light bulbs are flicker-free Energy saving, uses about 1/4 of the energy of a comparable Tungsten bulb, with about 10,000 hours bulb life Important: ALZO CFL bulb life is based on the bulb in an open air fixture with sufficient ventilation; when ALZO bulbs are installed in fixtures that lack adequate ventilation, the life of the bulb will be greatly reduced.