Turn this bulb on and you will see a purplish glow...stand near it and check out your teeth or any white bits on your clothes.
An energy saving Blacklite compact fluorescent light bulb with bayonet fitting. 15W B22 240V CE. Bayonet fitting.
Blacklite is Ultraviolet light which our eyes can't see. What we see under a blacklite is phospor - a substance that responds to the UV light.