black light bulbs

Does anybody carry a f15t8-bl bulb within the Bowling Green area or near by. I am looking for the bl bulb( white flourescent) not the blb style ( blue bulb). I can get the blue bulb at Walmart and places, but they are useless to me. I"ve found several of them on line, but I am alittle confused about the length of the bulbs with some of the sites. The lengths they give are all alittle off from what I need. How are they really measured anyway? I have an older Able2Products light which Sloan bought out several years ago,so it is built like the Sloan. Thanks for any help.

we carried them at the do it best hardware store i worked at maybe you can go to one around there and see if they have them.