The AquaticLife 34 inch, 420/460nm Actinic 39 Watt T5 HO Fluorescent Lamps are 34 inches from end of pin to end of pin (for 36 inch fixtures/retrofits).
The 420/460nm Actinic bulb spectrum is very beneficial to corals. With reef tanks half your bulbs should be actinic.
The AquaticLife T5 bulbs will work in any T5 fixture, as long as you are using bulbs of the same wattage as those currently in your fixture. T5 bulbs come in two categories, HO bulbs (24W, 31W, 39W or 54W) and NOs (9W, 14W, 21W or 28W). T5s are 5/8" or .625" in diameter.
