Huge numbers of badges were produced at the height of the Cultural Revolution, from 1966 to 1969. As a vital part of the cult of Mao, each badge carried his image. The majority showed his left profile, intended as a symbol of his leftist beliefs. Materials ranging from plastic and bamboo to gold were used to manufacture badges, but aluminium was by far the most common material. Porcelain badges such as these were actually produced for only a short span of time (about a year). Their fragility may have contributed to the decline in their production. Many different organisations produced badges that included the central government, army units, factories and revolutionary committees. Badges were created by different groups as an emblem of identity, to commemorate special events or to serve as rewards for model workers.