FOUR PACK This is Bulk lamp. It's an AquaticLife branded lamp (the logo is on the bulb), but it does not include the retail packaging. It's comes in a plain brown box. This is the only AquaticLife actinic 22 inch, 24W lamp that is still available. You can use this lamp instead of the 420/460 lamp. For a lamp with a more bluish look you can get the Giesemann Actinic Blue 24W 24' T5 HO Lamp. For reef aquariums we recommend half of your lamps be actinic and half full-spectrum daylight. You can use this in combination with the AquaticLife 22 inch 14K 24 Watt T5 Fluorescent Lamp for reef aquariums. The 14K is a full spectrum lamp. The AquaticLife 22 inch, 460/620nm Purple 24 Watt T5 HO Fluorescent Lamps are 22 inches from end of pin to end of pin (for 24 inch fixtures/retrofits). AquaticLife Part# 410223. 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. The 460/620nm Purple bulb spectrum is ideal for acroporas, anemones, clams, hard corals, leathers, mushrooms, polyps, soft corals and xenias.