In the 1940s, Selmer began producing Signet Specials that included a guide for the top trill key and the company insignia imprinted on the instrument barrel and its other pieces. The company stopped using the barrel insignia and the guide in the mid-1950s, but reinstated the guide in 1960.
Selmer USA manufactured clarinets under the Signet brand as early as the 1920s. Signet clarinets manufactured before World War II had features such as easily adjustable keywork. Selmer used barrel pivot screws for its Signet line, which included the Soloist, Special and 100. When the keywork fits exactly between the posts, the keywork pivots on the barrel screw to the bore of the keywork. In 1955, Selmer began using tan leather cases for its Signet clarinets; however, by the end of the 1960s, the company was making the cases out of fiberglass or black plastic.