TrueLumen T-5 HO Lamp 24 watt Actinic (BULK) This is a BULK lamp. It's a TrueLumen lamp without the retail packaging. TrueLumen 24W Actinic High Output T5 Lamp. 22 inches from end of pin to end of pin (for 24 inch fixtures/retrofits) 460nm Actinic Blue The TrueLumen T5 bulbs will work in any T5 fixture, as long as you are using bulbs of the same wattage and length as those currently in your fixture