Tube lights come in several flavors, but there’s a clear winner you should pretty much always choose.
You’ve seen the T5, T8, and T12 stuff, right? Well, the ‘T’ just means tube, while the number denotes the diameter in eighths of an inch. Therefore, a T5 is a tube light with a diameter of 5/8 inches. Tube lights can come in any length, but 1, 2, 4, and 8 foot are most common.
Also, tube lights will often come in a large fixture with multiple tubes. These are meant for scaled-up growing operations and are accordingly more expensive.
As it turns out, you should really only ever buy T5 lights. Both of the other kinds are older technology that is significantly less efficient. T5s last longer, use less energy, and produce more light.