T5 fluorescent technology is the leading way in efficiency. Combine the reflective efficiency of the parabolic reflectors and the energy efficiency of the T5 lamps and you have an extremely powerful combination. Another very strong point is their life span. Some manufacturers say T5 lamps can last as long as 24 months.
Parabolic clip on reflectors (31"x 2"x 1")
Universal or Sylvania T5 HO ballast runs 2 lamps (16.75" x 1.25" x 1")