Abstract: A ribbon cassette or cartridge comprising a housing having a hub element supporting a core having a ribbon wound thereon, such as a typewriter or printer ribbon, and adapted to releasably engage said core for rotation thereon. The hub element comprises at least two portions, at least one portion being fixed to the housing of said cassette or cartridge, and at least one other portion which is attached for movement between a locking position, in which it makes frictional engagement with the ribbon core to substantially prevent rotation of said core on said hub element, and a release position in which it is moved out of frictional engagement with said ribbon core to permit rotation of said core on said hub element.