I think the linear T2 bulbs are still being used for aquarium lighting... probably not a whole lot of people using them now-a-days. I've used both T2 and T3 spiral CFL's (same wattage and color temperature) and agree with Hoppy's statement about light intensities being the same.The only T2 lights I know of are spiral CFL light bulbs. They give about the same intensity as any other CFL bulbs.