The graphic was further popularized in the early 1970s by Philadelphia brothers Bernard and Murray Spain, who seized upon it in September 1970 in a campaign to sell novelty items. The two produced buttons as well as coffee mugs, t-shirts, bumper stickers and many other items emblazoned with the symbol and the phrase "Have a happy day", which mutated into "Have a nice day". Working with New York button manufacturer NG Slater, some 50 million happy face badges were produced by 1972.