Very little information is available on the D-Lux Blue brand of tubes shown above. Serlin & Company, 129 Michigan Ave., Detroit, Michigan sold these UV-201-A tubes for just 2 months in 1925 in the Detroit Free Press newspaper. They resemble the Brightson True Blue brand very closely in diameter of glass bulb, blue color, and the red bakelite base, however, the red base is mottled with a slightly different color on the Brightson’s. The display/shipping box is also quite similiar to the True Blue’s. It seems to be a coincidence that Brightson Laboratories Inc. had offices in New York City, Philadelphia, Jersey City, Milwaukee, Boston, and Detroit. There could also be a connection to Mastertone who made a similar blue 201 A tube. Without more information, what is in this article will have to do.