The hyphenated acronym PSU-UGT signified the close relationship between the regional Catalan socialist party, the Partit Socialista Unificat (PSU), and the national socialist worker's union, the Unión General de Trabajadores (UGT). In line with the political views of these organizations, the portrayal of human figures on the postcards below takes on a highly muscular and almost mechanical form prevalent in artwork from this period. Aside from several postcards promoting the call to arms, the focus of this set was designed to encourage the contribution of workers and peasants to the Republican war effort.