CH-L 4' HO 54w Bloom Spectrum T5 Bulb 48" (3000k Flowering) 4 Pack HIGH OUTPUT Bulbs: Triphosphor coated. 54w 93.5 Lumen / per Watt for 2900 Kelvin/ 5,049 lumens per lamp High Lumen Maintenance : 90% over 10,000 High Lamp Operating Temperature : 35C