These tubes are predominantly used for insect traps and fly killers (insectocutor units), however they are used in other applications including industrial processes and special effects. Blacklight lamps differ from standard fluorescent lamps only in the composition of the phosphur which radiates most of its energy in the near ultraviolet region, peaking at about 350 nanometers.
I recently ordered 3 reflector spotlight bulbs. The arrived promptly but their cartons said "not for domestic use" although they appeared to be perfectly normal. However when I screwed them into a "working" light fitting they did not work. I contacted BLT but later took a second look at the fitting and bent the spring contact at the base up a bit. No problem, they all worked. (RED FACE). I had a nice reply from BLT explaining why the box said "not for domestic use" and offering a refund. I sent an e-mail congratulating them on their prompt service.