Hydrofarm's T5 replacement tubes offer HO light output at a great price. Full daylight 6400K spectrum and compatible for all T5 fixtures they offer. 54 watt puts out 5000 initial lumens per tube. 24 watt puts out 2000 initial lumens per tube. Replacement bulbsHO light outputFull daylight 6400k spectrumRated for 20,000 hours of life2000 initial lumens per tube