A tool body and at least one cassette for a milling tool. The tool body includes at least two identical insert seats, each insert seat being configured to support a cutting insert arranged to be mounted therein. At least one side contact surface is provided in each insert seat for supporting a bottom support surface and at least one side support surface of the cutting insert. The cassette has a peripheral side surface including at least one side support surface and at least one insert seat configured to support a cutting insert. The at least one side support surface and a bottom support surface of the cassette are configured to be supported by the at least one contact surface of any one of the insert seats of the tool body, the cassette being configured to be detachably mounted in any one of the identical insert seats of the tool body.