Eye Hortilux PowerVEG T5 4' HO 54W Florescent Tube PowerVEG can be used in any existing T5 54W HO lighting fixture The recommended height above the canopy of plants should be between 8"-16". The optimal height is 12". If using all PowerVEG lamps in one fixture, we recommend reducing the time the lights are on by 20%. This is due to the quality of the spectrum and the amount of UV coming from the light. If using a 50-50 mixture of PowerVEG and standard T5 lamps, no need to reduce the time lights are on. Promotes extreme photosynthesis for faster growth.