ALZO 27W Full Spectrum CFL Light Bulb 5500K, 1300 Lumens, 120V, Pack of 4, Daylight White Light Crisp, bright white light ideal for reading and tasks that require visual accuracy; CFL bulb has natural daylight balanced color temperature of 5500K; pack of 4 THIS IS A LARGE BULB THAT MIGHT NOT FIT STANDARD HOUSEHOLD LAMPS, see diagram above; 9 inch ALZO lamp harp will fit this bulb; bulb fits all medium base E27/26 socket; Dimensions: Length: 6.5 inches; Width (Diameter): 2.5 inches; Width (diameter) of base: 1 inch. Good for starting plant growth Generates very little heat, and all ALZO Joyous light bulbs are flicker-free; energy saving, uses about 1/4 of the energy of a comparable Tungsten bulb, and has 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.