Perpetual Calendar of the Proletarian Revolution, USSR, 1930s. A rare Soviet perpetual calendar from the early Stalinist era, designed in accordance with the short-lived revolutionary calendar system introduced in the USSR in 1929. Made of enameled metal with rotating cardboard date indicators, this desk calendar displays the “Year of the Proletarian Revolution,” month, six-day workweek day, and date. Flanking panels are labeled “Addresses & Phones” and “Perpetual Notepad,” characteristic of Soviet office culture. Decorative hammer-and-sickle motifs underscore its propagandistic role. Manufacturer marked: "Prompoligraf", Leningrad, Tainovskaya St., No. 112. The Soviet revolutionary calendar briefly replaced the Gregorian system with a continuous six-day week cycle, abolishing the traditional seven-day week. Rest days were fixed on the 6th, 12th, 18th, 24th, and 30th of each month, with the 31st regarded as a floating workday. This system was abolished in 1940, making items like this rare survivor of ideological experimentation. Condition: Good overall with light wear, minor surface cracking to enamel, and a small chip near the rotating dial. An important artifact of early Soviet bureaucratic life and revolutionary utopia. Dimensions: 18 × 19 cm.