Marlboro Selectrate filter
The Selectrate filter was a cellulose acetate filter used on Philip Morris' Marlboro cigarettes in 1955. The term Selectrate was used for marketing purposes, and appeared on the Marlboro box in the phrase "exclusive Selectrate filter." The use of the phrase was challenged because of the implication of selective filtration and because of the question of exclusivity to Philip Morris.
According to a 1957 PM internal memo about the Selectrate filter, the only thing that was exclusive about the "Selectrate" filter was its size and shape, as many other cigarette brands at the time used cellulose acetate filters. However, after being challenged on the "exclusivity" of the filter, PM considered ways they could make it appear more exclusive, for example by inserting a red-dyed dot into the filter.
Selective filtration by the "Selectrate" filter
The name "Selectrate" was derived from Philip Morris' claim (derived from internal research) that the filter selectively removed a chemical called "furfural." According to the U.S. Occupational Safety and Health Administration, in humans "Furfural is an irritant of the skin, eyes, mucous membranes, and respiratory tract." In animals it is "a toxin to the central nervous system, liver, kidney, blood, and bone marrow."
Marlboro Selectrate Filter King Size (1954 memo containing sales instructions for plugging Marlboro with the Selectrate filter)