This is a genuine Ultratec spare bulb, part MS5917, rated at 12 volts and 5 watts. It is listed as the replacement light bulb for the Ultratec MS5174 Cyclone fan, a fan with a built-in light, so you can bring the light back to life when the original bulb fails instead of replacing the whole unit. Check the voltage, wattage and fitting against your old bulb before ordering, as it is meant for that specific model. This part has been discontinued by the maker, so it is worth keeping one as a spare while stock lasts.