SunBlaster 901896 T5 High Output 2700K Replacement Lamp, 4-Feet High output 6, 400k lamps simulate natural sunlight and are ideal for cuttings or vegetative growth Some horticulturist's Choose 2, 700k for budding and blooming Sun Blaster T5 ho lamp produces a light of much greater strength than a conventional tube and, as a result, the energy input into the area being lit is much greater and the light penetration is FAR superior to anything previously available