Ribbon cassette for a printer

A cassette for ribbon for a printer, particularly a thermal printer, is disclosed. The cassette is configured to be stably mounted to a print carriage of a thermal printer, or to a storage turret mounted to the printer for storing a number of cassettes, and to be transferred by a passive transfer system between the print carriage and the storage turret simply in response to movement of the print carriage. A smooth, low friction path is provided for the ribbon within the cassette with no acute angle changes in the path when the cassette is in a printing position and being acted upon by the printer's print head. The cassette is provided with a brake mechanism which automatically engages the supply and take-up reels in the cassette when the cassette is removed from the print carriage, and automatically disengages the brake mechanism when the cassette is mounted to the print carriage. The cassette is provided with a bar code so that cassettes on the storage turret may automatically be identified, particularly for use in an automatic cassette transfer system. The cassette housing is plastic and is provided with an anti-static additive.