 The machines made use of technology protected by United States patents assigned to Mills Novelty Company, including number 1,869,616.In 1940, the Mills company introduced Soundies, short 16mm musical films played in a coin-operated movie jukebox, its projection and sound mechanism made by RCA.Wartime restrictions curtailed manufacturing of the jukeboxes, but the Mills company continued to produce and distribute new films for them into 1947.