What is T5VHO vs T5HO?

[Samw]

The UVL T5 bulbs are labeled as T5VHO.

http://www.uvlco.com/t5vho.htm

Aquatinics sells both T5HO fixtures and T5VHO fixtures so I assume that means there is a difference between T5HO and T5VHO. I bought the T5HO fixture. Does that mean I shouldn't use UVL bulbs? I don't see any UVL T5HO bulbs on their website.


EDIT:

Never mind. I just found my answer.

http://www.uvlco.com/index.htm

"Better yet, it is available in our NEW't5 V-HO lamp' format. The First of its kind, a "variable output" lamp which can work as either HO or VHO. Unique patented engineering allows it to last longer and run more consistent than the conventional T5 HO lamps on the market."