The T5 V-HO's are t5 bulbs that can be over driven. This was often done with Ice Cap or Coral Vue ballasts, and certain fixtures such as the Sunlight Supply Tek Wave T5 VHO Fluorescent Lighting Fixture, can run these T5 V-HO's bulbs at a higher wattage than the HO. These T5 V-HO's will give you more intense lighting, which will look brighter and offer additional PAR. I hope this helps.
Chris R.