Quantum T5 HO 4' 54w Blubs 2900k (Box of 8) VERY HIGH OUTPUT Lamps: Triphosphor coated. 93.5 Lumen / per Watt for 2900 Kelvin/ 5,049 lumens per lamp High Lamp Operating Temperature : 35C Good for Bloom High Lumen Maintenance : 90% over 10,000 hours